Intellectual Property, Copyright, and related rights

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BIG RED TEXT HELLO: This is not legal advice, or necessarily correct. Do not make legal decisions based on this. I'm just someone on the internet trying to figure this out. Ideally for general consumption, yet any of this is at best a introductory read before diving into the real choices/implications/legalese.

IP's practical concepts

Intellectual Property includes (but is not limited to):

Copyrights are exclusive rights on an original work/expression -

Primarily the rights...
to display in public
to reproduce
to sell, and
to make derivative works.
Copyright's intent is largely to stimulate and protect investment in a creative process, by rewarding that creator for some amount of time.
Violated copyright is often about profiting from someone else's work.
Violated copyright can be proven by showing whose work it is.

Trademarks give their owner exclusive rights to use a particular symbol or phrase to identify and distinguish a particular product or manufacturer.

Trademark's intent is arguably largely to ensure a product is what it says it is. Not protecting anyone, yet
For consumers in the same context, this is often not being misled by imitations, to have a decent estimate of quality of a product.
For companies this is largely about putting money into a brand to be recognized in that way.
(America also uses Service Mark to point out when you're naming a service rather than goods (particularly before registration?). Most other places do not make this distinction.)
Violated trademarks are often about misleading people about brands. This is, fairly literally, about trading on someone else's name.
Violated trademarks can be proven by showing people are confused in their purchases.

Patents give their owner exclusive rights to use a particular invention, i.e. a new idea and its direct implementations.

(In theory this is about inventions regardless of precise implementation - though in some fields that distinction is vaguer than you'ld think)
Patent's 'intent was to stimulate the willingness to invest in a research process, by rewarding the time and money invested in development, through giving the inventor a share for a limited amount of time.
Violated patents are about profiting from someone else's costly research (...well, that's the intent, not always the practice, or even the legal measure used in court)

Trade dress[1] can cover some ground the last three do not.

Trade dress deals with recognition of a product, or even its packaging.
Which can be very fuzzy, and arguably is protection of brand and marketing.
So in intent, it's arguably closest to trademarks.
It is e.g. meant to stop counterfeiters from making things that look almost indistinguishable except from e.g. a slightly different logo that lets them "well technically..." their way out of it being a trademark violation.
Fake handbags do that, for example.
For another example, when tablet-style computers were still newish, Apple sued Samsung when their tablet started physically resembling the iPad a little too closely - which would not be a patent violation due to different tech, or trademark because they did mark it clearly (enough) with their own brand.


Genericised trademarks

Genericised trademarks / generic trademark refer to trademarks (typically brand names) that became an everyday term.

Note that it having become an everyday term does not mean the trademark is not enforceable, though it is not always great PR to do so.

See also the closely related trademark erosion, a.k.a. genericization or genericide, referring to variants where the trademark is effectively lost (due to its practical requirements).

Examples of genericised trademarks include

Band-Aid (for an adhesive bandage),
Kleenex (for absorbent tissues),
Google/googling as a verb meaning 'searching the web',
Velcro (for hook-and-loop fastener),
Chapstick (for lip balm),
Tupperware (for plastic food storage),
Crock-pot (for any slow cooker),
kapton (for polyamide tape),
Post-Its (for sticky notes),
Popsicle (for ice pops),
Hoover (for vacuuming),
Xerox (for copying, named for the copying machines, though this one is relatively local, and may now be falling out of style),
Q-tip (for cotton swabs),
Alka-Selzer (for antacids),
Styrofoam (for polystyrene foam),
Plexiglas (for polymethyl methacrylate),
Ouija board (for a spirit board),
Softies (microphone wind protection),
hacky sack (for footbags),
Sharpie (for permanent markers),

and many others.

Note that various can be understood both generically, or to the original product - e.g. a Sharpie may be a permanent marker, but many people will still mean the specific branded one when they say Sharpie.

Also things like bubble wrap, jet ski, dumpster, and onesies. These were arguably more descriptive to start with, and only distinctive enough to be recognized as useful names, but not necessarily distinctive enough to be clearly recognizable as a brand.


This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.


This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

Basic copyright

Copyright intends to protects the cost and effort put into original works, from being exploited by others not putting in that effort.

Copyright makes it worth it to interest nontrivial time to make something creative and original.

Copyright is what gives you rights on an item to

  • display the copyrighted work in public
  • reproduce
  • sell
  • make derivative works

Since you own these rights, you can choose to authorize others to do some or all of those things, as well as transfer them completely.

Copyright does not need to be registered anywhere. (anymore)

Since the Berne Convention, copyright automatically applies on anything tangible you create, as soon as something is painted, written, or whatnot.

(...'tangibly' / 'fixed' is a historic thing. Digital forms are a little less clear-cut, though laws are slowly catching up.)
even when it applies anyway, there may still be a few upsides to registration within a country

Phrases like "All rights reserved" seems to originate from the earlier (1910) Buenos Aires Convention, and seem intended to denote that copyright in one country extends to all that adhere to this treaty (which was mostly the Americas), but seems to have no legal meaning elsewhere (and isn't necessary since Berne, since it doesn't add anything to what Berne covers by default(verify)).

It's still a practical way to signal you might care enough to make a legal point of it.

(relatedly, you may care about Universal Copyright Convention of 1952)

Copyright goes to the author

If you create a work by yourself, you now have exclusive rights - meaning no one else can use it without your permission.

...with a few footnotes. And exceptions, in particular work made for hire, which often comes roughly in two forms:

  • employees
In practice, if something falls directly within the scope of a job you are hired for, your employer gets the copyright
The wording also means your employer can't steal your hobby projects,
related people going into business for themselves, creating a new distinct thing in the same field, is often fine, but take care
  • commissions
commissioned work is the creator's and not the commissioner's, unless you explicitly sign the rights over
It is in the interest of both parties (and also fairly typical) to have a contract with specific mention of transfer
for artists, to specify details that may be challenged later, including attributions of style and originals
for commissioners to get rights, limited or not, in the first place. Useful if you e.g. want to show it to people (which is frequently also in the artists's interests).

You can make agreements otherwise, but you will want that in writing.

A copyright notice is not necessary for copyright to apply.

...anymore, in most places.

For example, in the US it was required until 1989, and Night of the Living Dead (from 1968) forgot to do so, and was considered public domain because of it.

Since 1989 in the US, copyright is default on new works.

It's common enough to see a copyright notice: copyright symbol, date of creation, and copyright holder name ("all rights reserved" used to be required, now optional).

This is not required, but is an easy signal that you care about the copyright, and may make it easier to prove later that you were always the author, and make make it easier for people wanting to license the work to contact you, etc.

It may also avoid the innocent infringement defense, which amounts to saying "..but I didn't know it was protected", which was never a great defense, and in most cases won't stick legally, it's just that if there is a notice, they more clearly have no case.

Further notes:

  • Copyright applies to public use, not private use.
roughly because there is very little to exploit privately.
  • Granting these rights has to be done in writing - just saying it's fine is not enough
  • Individual (or even full) rights can be granted on a case-to-case basis, but also on a blanket basis.
in some areas it's common to draw up a contract at the same time you sell an item
  • When copyright holders are individuals, they're often not not very picky about granting them, particularly for individual and non-commercial use.
When holders figure something may be sold, then you often deal in conditions and money (quite expectable when holders are are businesses)
  • You could make any agreement that holds up legally. A work can be sold, and/or rights granted. For example, a work...
...can be sold with all rights (e.g. original works)
...can be sold / loaned with some rights restricted (consider music, DVDs, etc.)
...can be due to royalty fees when publicly displayed/reproduced (consider music)
...can have specific uses granted, e.g. allowing it to be put on shirts
...can have uses granted for a limited area time, e.g. reprint rights in america for two year, internet post rights for one year, or whatever. Also relevant for 'limited edition' things. Usually only worth doing on valuable IPs

  • "royalty-free" does not mean "copyright free"
Royalty-free is a copyright agreement that says "we won't charge you for using this publicly" - and often with specific conditions, e.g. type of use (where, how)
the agreement itself
may still be for money - e.g. there are paid-for royalty-free stock image sites, often resellers with their own pricing model
or not - there is gratis royalty-free music online [2] without charge (often from the artists themselves)


Some practicalities

International copyright

International copyright for a large part does what you expect, but it is not a given, and copyright specifics do differ per country.

And due to how the agreements on copyright developed over time, countries basically apply their own copyright law to foreign copyrighted material.

Legally, a large chunk of the details that matter internationally seem to come from:

Copyright length

Copyrights run out.

When they do, the works pass into the public domain (though note that the term Public Domain is a US-centric one).

Because the length is settled, there is usually a date before which almost everything is public domain (either because there was no copyright or because it has expired).

For example ~1922 in the US.

Internationally, most books before 1945, and every book before 1787.

More recently, it depends on:

  • when it was made,
  • what type of work it is (different lengths apply)
  • whether the copyright was extended (if possible)
  • possible other specifics
  • possible legal changes (e.g. in the US and other countries, copyright length has been repeatedly increased, from ~30 to ~100 years)

Copyright assignment

Copyright and the internet


If someone infringes, you can of course ask them to stop doing so.

This can make sense if you think a person just liked the work, and/or you can often easily come to some agreement or other.

In case of more willful abuse, e.g. someone intentionally profiting from your work, the best idea is often to consult a copyright lawyer to weigh your options.

In practice suing will often cost more money than you'll get in return (and in some cases may get you bad publicity), though it is likely a useful way of stopping the infringing.

Uncopyrightable things

This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

Under law, there are a number of things that can't be copyrighted. The rules and lists vary, so check your local details.

In the US: (most of this is copy-pasted from

  • Titles, names, short phrases, and slogans; familiar, everyday symbols or designs; variations of typographic ornamentation, lettering, coloring; listings of ingredients or contents. (some of this is trademark stuff instead)
  • Works that have not been fixed in tangible form of expression (for example, choreographic works that have not been notated or recorded, or improvisational speeches or performances that have not been written or recorded)
  • Works consisting entirely of information that is common property, containing no original authorship (for example: standard calendars, height and weight charts, tape measures, lists or tables taken from public documents or other common sources)
  • Ideas, procedures, methods, systems, processes, concepts, principles, discoveries, or devices, as distinguished from a description, explanation, or illustration

Particularly in the first and last case, but also in general: note that patents and trademarks are different things and may still apply.

On crediting

Say you add "I do not own this. All rights belong to the creator, [name] and [link].", and possibly legalese-sounding stuff about not profiting off this copy. That fixes it, right?


Only asking the person for permission, and getting it, changes anything.

Copying and crediting has no legal effect - you're still infringing, you're just being a little nicer about it.

(...nicer than e.g. freebooters, e.g. copying popular videos to their own channel to get ad revenue for it. And even if you make no ad money from your copy, you are still taking away from their ad revenue)

The ethical standard (and ideally the legal one too) becomes whether it affects the creator's ability to sell the thing, and keep making things like it. After all, the idea was protecting creation.

What the actual consequences are depends on what the artist/owner wants.

If it's the odd shared image on social sites, they might decide it does as much good as harm to them, so making a fuss may not be worth it.

If it does have a real influence on their bottom line, then they are more likely to take action (including when a company is the infringer, which is a clearer case of being exploitative).

This is also part of why "I gave them exposure" is not a legal argument (it's also often not actually true at all, but that's something else).

It's also why removing copyrighted material later doesn't nullify the effect it had earlier.

Fair use

Fair use describes exceptions to copyright, cases where a use would normally be infringement, but for specific reasons is not.

Fair use is also the area of many myths, and more than a few legal cases.

The most useful angle to focus is whether it serves a different purpose, for consumers of the thing. In legalese, whether it is transformative.

Transformativity is certainly not the only factor, yet it's the one you would pick in introductions like this, because it tends to imply the other relevant ones as well.

If copyright's main intent is to protect a creator's investment in a creative process, then if something is not transformative, it will easily play in the same market that the copyright holder of the first work does.

If so, it will easily take some of that same audience and have them view and pay for that derivative instead of the original - at the cost of the person who created that market in the first place.

The clearest case would be digital piracy/freebooting - plain copies of the thing.

Yet there are many other types of content piggybacking that you can find now.

Rewarding low-effort copies amounts to not rewarding original creations, so if we collectively value the creation of new things of quality, there really do need to be rules about this, and copyright is currently the most viable way.

On the other end of the reasons ans spectrum there are uses in research, reviews, parodies, many of which are considered transformative, not because of the category but because they typically don't serve the same purpose, so chances are much better that it won't affect the original creation's market.

Examples and myths

"You're making money, it can't be fair use" / "I'm not monetizing, so it's fair use"

Monetization has no direct bearing on whether the use is fair use.

In that you can make money while not drawing market/audience away from the original creator.

Sure, in practice it will be hard to do this, to have no legal issues, and do it this consistently enough to have it be a stable income.

Practically, money being made is certainly still relevant to

how quickly people will want to look at your case,
and how thoroughly people will try to find other reasons,
and how interested they may be in a legal battle in the first place.

"If I add 'this is fair use', 'no infringement intended', and/or pointing out the real copyright owners, that makes it safe"

In general, this legally changes absolutely nothing.

Because none of that changes any of the just-mentioned points about audience and market and such.

Depending on the case, copyright owners may be somewhat less likely to sue you, but often for other reasons.

Educational uses, use in research, use in news reporting is fair use

Yes, but not because because of what that field is.

And instead because of what you do in these field is easily transormative.


A video fragment in the news mostly mainly shows the context.
If you're studying a thing in depth, you may even end up showing much of the work, but most of your content may still be that study.

At the same time, it's absolutely possible, within each of those fields, to violate copyright.

It doesn't happen nearly as quickly, but still very easy if you are trying.

"Using short fragments makes it fair use"

It's not the fact that they are short.

But shortness can imply other things that do matter.

Most uses that need only a short fragment are things that don't play in the same market. For example, showing a scene from a movie and then saying "this is good example, now here's a discussion, which is the actual content here".

This is a good part of why uses in educational, research, and news reporting tend to be fine, and also part of why critical review, response videos, video essays, and such usually are as well.

It relates to why parodies are quickly fair use, because its nature is the criticism of the actual content, often distancing it from the content itself. Though the gradations often involved means parodies are a topic of their own. If you imitate a thing and stick 'parody' on the title, that may not hold up if it gets to court.

Sure, in practice people will probably check how of that content there is, and compare it to the amount of shown content.

Show one or two scenes, then talk about it for a dozen minutes? Probably fine.

Show a dozen minutes, then make a short remark? Assume no. (In part because you could watch what amounts to mostly the the original wprk that way.)

"If changed more than 10% it's fair use / not infringement"

There is no magic percentage, or timespan, or such. While contents matter, use matters more.

Maybe just ask a random person on the street. Do they say thing A is similar in purpose to thing B? Then you're probably on dangerous ground.

"If I talk over it it's fine"

Can be, but it depends.

Say, youtube response videos will often talk over the thing they're reviewing.

Or maybe show it muted. Or maybe show a short piece looping continuously. These things are intentional, because it's enough for their content, and makes it hard to consume the original content as originally intended.

(Specifically on youtube, where claims are fairly automated, another point is also that the way the content ID system is enforced is rather biased to punish creators, so even if they're in their right, creators want to avoid this. These masking (flip it, make it half transparent, put some text over it) techniques aren't sure to work, but it really can't hurt.)

Say, if you're responding most of the time, that's fairly clearly transformative.

Yet if you show an entire movie, you'ld need to do serious amounts of yapping for it to not maybe amount to a public showing. And people probably wouldn't watch the result.

Case in point, MST3K licensed most of the movies (and presumably found a few with expired copyright?(verify)). Not because it wasn't transformative - you can argue that it often was, and maybe they would've usually been fine. Yet they made a decision that the risk and cost of lawsuits probably doesn't outweigh getting that license.

(RiffTrax was an audio-only thing because that removed all worry, providing the same fun with only a little syncing for you to do)

"If I change the lyrics, it's fair use"

That depends.

Music is actually a weirdly complex case, and has recently gotten messier and more detailed over time.

In many places, the composition and recording receive separate protection, with their own logic to them.

Sampling is its own thing that can get you into trouble even on an otherwise original creation.

Covers are also a complex topic.

That said, play a silly version with different lyrics, particularly in criticism, and you may well be fine.

If you're just making it sorta-kinda-different but mainly clear reference, not so much.

And, while the risk is yours, you probably don't want probably-stuffy lawyers making the decision for you.

Case in point, Weird Al, probably the most prolific parody artist since the eighties, asks for permission (and apparently licences(verify)) all of his songs.

He may not need to, but it's less worry than the legal nonsense.

Apparently he does have a dozen songs where, while the law would probably be on his side, he just won't release because the artist didn't approve. Presumably it's a mix of principle and 'not worth the potential legal bother'.

copyright claims

spurious copyright claims


Copyright free, Public domain, similar

This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

Copyright free, most literally, means works for which no copyright currently applies.

Which can happen from

  • action - explicitly given up
  • inaction - expired, or whatnot.
  • legal implication - such as that some governments saying that copyright will not apply for certain types of their output - see also public domain, below.
this also roughly means that copyright cannot apply.

In many cases, copyright on exactly the same cannot be (re-)claimed later, so a copyright free work can be used without much risk.

That said, you could use it in a new work that is then copyrighted. Not even preserving the original author's name is required, though this is often considered good style.

Consider even if copyright, other IP concepts may still apply. Consider e.g. publishing with trademarks that you do not own.

Public Domain is arguably a more specific idea, yet in legal terms arguably less meaningful.

The wider concept describes cases where no exclusive intellectual property / copy rights apply, due to being inapplicable, or expired, forfeited, or waived, or sometimes just practically that no one could make a good legal claim to own it(verify).

Yet the thing we call "Public Domain" is a US-specific concept, existing as something of an addendum to US copyright law.

The idea doesn't appear in every nation's laws, and where it does, it may not be legally equivalent.

As such, works that are PD in one country might have some restricted rights in another. (In fact, the practicalities seem to vary a little even within the US.)

In practical terms, the boundary between "entered enter the public domain" and "became free of copyright" are not legally the same.

Consider for example:

  • via an outdated (not renewed, or not renewable) copyright
example: 1913 version of Webster's dictionary
see also
also note that some countries let you renew (extend) it a lot easier than others.
  • by legal implication, such as by being released by the US government, and a number of other countries do this too
example: the CIA world factbook
  • by explicit release
has been questioned - see below
example: the Moby lexical resources

Being public domain is not a license.

Nor is it the lack of one, precisely, in that PD also describes works where no one could make a good legal claim to own its copyrights / intellectual property rights(verify). Anymore, or sometimes at all.

When and where copyright exist on new works by default (that is: most places since the Berne convention), public domain is largely about copyright eventually timing out.

There is a real distinction between a lack of a license, public domain, and and a license that grants all rights to the public

Not declaring a license on a new work will, in many places, default to giving you copyright.

You can stay copyright holder but say all those copyrights are granted to everyone(verify)

To say you release it in the public domain (assuming for a moment that you can ) is saying you no longer have a claim to it.

Public domain may not mean free of all possible lawsuits

...the above also means that someone else can take something in the public domain, change it slightly, call it a new copyrighted work, and then sue you for violation because the original is so similar.

If that sounds like frivolous american litigous fuckery, yes, but also it's a valid legal concern.

Say, Getty Images has repeatedly gotten into hot water over issues like this, taking images people have explicitly donated into the public domain, requiring people to pay to use them using very copyright-like terms and under threat of making a court case of it.

It's not that they charge for public domain images - that's legal, if potentially sleazy when they pretend they own it.

It's legal threats over something they don't really own (but if you bend the wording enough, can make a case of), an argument that wouldn't hold up on court, but will scare enough people.

It is questionable whether you can actively release something into the public domain

e.g. US PD law only mentions it as an implication of having been dead for a long time (and having no heirs to lengthen the copyright). (verify)

Sure, when they try to release it this way, the person who released it is unlikely to care about copyright later - but they might be within their right to do so. That said, there is probably legal claim to be retroactively be annoying about it

Still, if true, there is a difference and it is not the handiest thing to use as a license.(verify)


If you don't mention a license, then it depends a little on the place, but assume it's copyrighted to its author - see the Berne convention (there are further details, though). Or employer, if that applies.

A license that grants all rights to the public may technically still be under an individual's name, but relieves all (mentioned) uses of any legal implications

Public domain means it is no longer anyone's and there are no legal implications to use.

Public Domain is not an international concept

That is, the term is from the US, and some of the described details are also US-specific.

The idea, and the execution of that idea, lives in many places, yet the name and its details may vary a bunch.

As such, saying "I release this into the public domain" may not do what you want it to do.

In the US, and/or elsewhere.

It may not technically do anything.

If you want to say you license it to the public, this is different from you don't want a license, in what other people can do with it. Same idea, different technicalities.(verify)

It is not clear whether "release into the public domain" is a thing.(verify)

It has been questioned whether, even in the US, you can explicitly do this at all in a way that is actually legally does what you want it to.

In practical terms it may be similar enough, simply because if you technically still hold the copyright, it's clear you won't go after people.

It is also not clear whether you would win a case if you said "no actually it's copyrighted" later(verify)

You may not be able to release into the public domain

Sure, if you say so, the intent is clear.

If the author technically still owns the copyright, they're unlikely to enforce it still. I'm not sure a case has ever happened where someone has tried, and what happened.

Things changed over time

  • Berne convention was a big change for many countries
  • China had a fifty year period without copyright, but they certainly have copyright now.
  • In the US, copyright by default is a relatively recent thing
copyright being there by default on any newly created work, without explicit copyright statement, is only a thing since around 1989. Before then, things were in the public domain by default(verify).
For example, the movie Night of the Living Dead (released in 1968) was considered public domain because it forgot to add a copyright indication[3], and US copyright law required this at the time.


  • the idea that 'public domain' means "when it's out there, no longer copyright", e.g. if it's out on the internet, copyright protection no longer legally exists
copyright absolutely applies. You may' have some issues getting all copies taken down, particularly if you can't prove ownership.
but the internet is not a copyright bleaching machine

  • Online, 'copyright free' is often confused with 'royalty free' (a lot of royalty free works are definitely copyrighted, with some specific terms).

See also:



Given the above, saying something is public domain is fairly informal description, and legally, it can make a lot of sense to more explicitly state intent - that you intend to make no claims.

Even if those terms are a short bit of text, it is more explicit, and it's also a fallback license for places where public domain, by that name, does not automatically apply.

...or isn't really a thing at all. Again, stating intent to do nothing is clearer than the absence of statements.

CC0 is one of several things that explains things along these lines -- similar ideas include the WTFPL and the unlicense(verify).

See also:


The Do What The Fuck You Want To Public License is intended to be equivalent to releasing into public domain.

See also:

The Unlicense

Another license that explicitly tries to be the equivalent of public domain.

It's three paragraphs, roughly saying

you are free to do these specific things copyright usually prevents you from doing
we dedicate copyright to the public forevermore, to the degree local laws allow
use this work at your own risk

See also

Semi-sorted (copyright)

Database rights

Poor man's copyright

Content ID

See also (copyright)

(Chain) (software) license comparison

Note: Most licenses here are software licenses.

Most are also chain agreements, where copying/using implicitly agrees to holding up the same terms, which can form a copy-and-agree chain.

This is different from basic copyright, in which you only deal with the copyright holder, which is often the single original creator (or distributor) of the content.

How do I choose?

This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

There are a number of interactive things.

I like this one:

Potentially confusing points


This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

Free software

Free software deals with liberty of use in the wider sense of the term, in the sense that any recipient has no legal barriers which would inhibit their freedom to use, study, modify, or redistribute the software. (paraphrased from wikipedia)

Also described as 'free as in speech' , libre, freedom in a general sense - a 'I can use, a tinker will at, a "no one gets to say I cannot".

(Free software licenses often emphasize such "yours to do with as you please, and hand it to someone else to do the same" points.)

Open Source Software, OSS, deals with the availability of source code.

At the very least, open source implies that you can look at its source.

In most forms of OSS, this also implies you can use that source code (and its compiled form) e.g. for personal use,


...but not necessarily mean you can run it a business
...but not necessarily mean you can make money off it
...but not necessarily mean you can use it with your neighbours
...but not necessarily mean you can redistribute mopifications

Whether you do or don't have those rights depends on other parts of the license agreement.

Classically, almost all OSS is also Free software, in which case you can do all those things. Free Open Source Software, FOSS (also sometimes FLOSS or F/OSS), which was always a thing, has become more relevant than ever.

FOSS is probably the thing you were thinking of if you're a idealist:

You can not only see the code, you can also use it, and change it, and code can be easily shared back.

depending on the license, you might have to share it back.

...but particularly in the 2010 and 2020s, more business are playing with exactly the distinction of "Open source but not free software".


  • we often say 'open source' meaning 'free open source'
  • The difference between free and open software can be subtle in its definitions, but can be pretty clear in its implications
so look at what it tells you you can't do, what you need to pay for to do
  • People like Stallman have pointed out that there are some distinct freedoms that free software aims to make free:
The freedom to run the program for any purpose.
The freedom to study how the program works, and change it to make it do what you wish
The freedom to redistribute copies so you can help your neighbor.
The freedom to improve the program, and release your improvements to the public, so that the community can benefit.
  • ...and from that view...
open source gives fewer guarantees, free software gives more, and F/OSS gives most
free software is more an implication of the license you put on it
open source is mechanically easier to do - you put the source code in a place where people can read it.
but note that it may still be under a license that say "we will sue you if you do anything more than look at it"

  • neither freeness nor openness refers to pricing to the end user ( 'free as in beer' , gratis).
As long as the applicable licenses do not specifically restrict it, free and open source may well be sold.
you practically won't get people to pay for much more than distribution costs, when the code is available and they can reasonably copy/use the thing themselves
that said, there are sensible and profitable business models based on free and/or open source software
the most common is probably selling support services, or easing administration at scale, which some linux distributions have successfully done.
  • It has become more common to do things like
    • dual-license stuff that works like "you have most freedoms for personal use, but commercial use has more details".
    • use the open-core model, in which most of the workings are open source, but some fancy features are not.

See also:

...and "source-available"

This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

"Source-available" means "you can look at the code, but not necessarily do anything with it".

These has fewer of the freedoms like modifying, or even using, so it does not meet the criteria of free software or FOSS.

Technically, FOSS and OSS is always source-available, and source-available does not necessarily mean FOSS and you can draw some venn/euler diagrams if you want, but...

Practically, the term 'source-available' primarily comes up to point at things that are clearly not free software or open-source-as-commonly-understood.

...particularly when companies make something source-available and proprietary at the same time.

Sometimes the only leftover public benefit is that security review is easier, and even that is only a public benefit when it is a widely used service. (...assuming that source actually matches what you installed, of course.)

(All this is one argument that many people, when saying 'open source', should be saying FOSS.)

Source license, non-source licenses

Licenses may be explicitly specific to certain content types.

Source code, 'cultural works', documentation, others.

Many licenses discussed here are source-code licenses, in that they are written with terminology meant for source code.

Which is necessary due to the way source gets combined.

Recently, copyleft licenses specific to text, metadata, video media, audio media, datasets, and more have appeared.

The details can matter to how the license's wording applies to the kind of work.

Copyright and copyleft, 'Chain agreement', 'viral license'

This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

Basic copyright applies implicitly and default, in most of the world

You make something, it's copyrighted, as implied by the laws that apply to everyone in a country.
(see Berne convention and related)

In contrast, copyright agreements are between people.

For example, businesses classically deal with intellectual property via basic copyright:

there is a single content owner,
often its creator or their employer,

and you can seek them out and sign some agreement, often a "you can use this copy"-style copyright agreement.

These agreements usually alter and extend a specific right, and often apply just to the (two-ish) parties directly involved in making that agreement.

Point is, the setup is centralized - there is one owner, and sometimes agreements with them, and just them.

A different apprach to the whole thing is a chain agreement where, due to the wording of the license,

if you take any version of the content,
you use it under the terms of the license (rights, obligations) it was released under,
where those terms include clauses that e.g. mean the license must apply (partially or fully) to that new version as well

No matter what derived version you are looking at, the license says that you can take it, as long as you adhere to the text to the license.

That license wording means it makes legal sense without a central owner.

There is no central owner to impose the terms and exceptions, it is the license wording that imposes the terms (and generally no exceptions).

Copyleft is often considered a reciprocal license - copyleft tends to refer to construction that says

if you alter and use it, you must show your work.
...and you must use the same license on that

This is often a chain license. Each license has its own take on freedom to use, study, copy, modify, and/or distribute, but they tend to say most of those must stay.

The variation leads to a useful distinction between strong and weak copyleft:

Strong copyleft perpetuates all its restrictions.

The GPL is a common example because it is easily explained: If you pick up something GPLed, you may only release it under the same terms - no more, no less.
In other words, no matter how much that GPLed content evolves, it will stay GPLed.

Weak copyleft means licenses where there are situations where fewer restrictions apply.

They still perpetuate themselves and say 'show your work', but have fewer requirements (details varying with the license)
Examples: LGPL, MPL

Permissive licenses are typically seen as distinct from copyleft.

They do not require you to distribute changes, and so allow you to close the source
typically the largest obligation is to mention where you took it from.
Examples: MIT, BSD, Apache, and others,


  • library licenses are often a mix.
Take the LGPL, it basically has a "you can use it as a functional unit without restrictions, and the license doesn't affect code outside the library -- but if you change the library itself you have to give back" sort of attitude.

  • GPL is strongly copylefted, a nature which can be seen as both a strong and a weak point.
Strong point in that it's a very simple way to keep the code in the community, which is good for the code itself.
Critics call it a viral license (or even toxic):
once source becomes GPLed, it can't really become licensed under something else
existing GPLed content is very hard to multi-license
...legally entirely possible, but it's usually prohibitively annoying to do - because it means you need to find all past contributors, and get them all to agree.
GPL also puts a lot of force on code you want to use alongside - it basically has to become GPLed as well.
This occasionally means that GPLed software cannot be adopted into certain projects, because it already had code that is either proprietary, or also commonly, under a different license that cannot combine with the GPL -- which is what the term notes 'GPL compatible' is about.
(This is one reason to consider using the LGPL if you can)

There is an argument that historically, GPL was a very useful thing for open source to become a thing in a largely-proprietary market - that these days the same sternness is not useful, and there are more business models where more permissive licenses make equal sense - and lead to more collaboration and cross-pollination.

This is a philosophical debate about what exactly it is that you want to flourish in the long run.

False open source

'Substantial portion'

Various licenses state that they apply when the software/document are used in full, alternation, or use of a 'substantial portion' .

This is inherently fuzzy.

Sometimes intentionally - it allows people to copy habits and good structuring ideas, while not allow them to copy-paste the entire project.

Derivative work


Multi-licensing refers to giving a choice of more than one license to use.

Multi-licensing (often just two, i.e. dual-licensing) is not directly about license compatibility. You can multi-license using various incompatible licenses, because it is a "choose one of the following" situation, and the next person only agrees with one at a time .

When one of the two is open source or free license and another isn't, this doesn't exactly make make things easier, and may mean the software takes two different paths over time. However, there are some situations and business models in which this makes sense.

To take a real-world example, the Qt library can be used in two ways:

  • under the paid-for QPL, which allows you to use Qt in proprietary programs without having to release anything, or alternatively
  • under the GPL

Free software projects use it under GPL terms, and the core of the Qt project thrives from that. In addition, you can choose to use it in proprietary code (without having to open anything up) and have to pay for that ability. (And you could develop a variant of Qt, but you probably won't as you can only use it yourself, and there's value in keeping it compatible with newer developments of Qt)

In many situations, dual licensing has proven a bit of an anti-pattern, because it doesn't really give you or your customers anything, and it does still make your life harder.

License compatibility

This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

Licenses consist largely of restrictions.

When combining two different pieces of software into a derivative work, both licenses have something to say, and these restrictions may be directly at odds.

"Derivative work" is a whole another can of words: When is it two things entangled into a single derivative thing, and when is it just two things talking to each other? This was clearer in the time of monolithic executables, and vaguer now that everything is much more modular.

But let's talk about the clearer cases of taking two parts and smashing them together into a useful single product that you want to release.

These licenses typically only have things to say when you distribute a combination - mainly because of the logic behind the copyright law this is all duct taped onto. no, there are no legalities to whatever tinkering you do in your cellar as an end-user. But you should still care about it if you ever want someone else to using your nice tinkered thing.

Legal basics of combination

This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

When you combine code with different licenses, both the licenses apply at the same time.

And you can't have a legally self-contradictory combination.

So various combinations simply are not legally valid (to distribute).

Broadly speaking, the largest difference here is permissive versus copyleft licenses

Permissive licenses like MIT, BSD and Apache says author attribution lives on, and little else.

It says little else. In particular, it means that these allow re-licensing of the derivative work.

Copyleft licenses (and pretty much everything else) have a "same license for all derivations" clause.

That means any legal contradictions you find cannot be resolved, and the combination is considered just... incompatible.

This happens quite easily. A good example is the 4-clause version of the otherwise-very-permissive BSD license, which says "Advertisements mentioning this software must acknowledge its origin/contributors".

And even though I'm sure the people who wrote the GPL like the idea, the GPL says "no more, no less than we required" and this is an additional restriction it does not mention, so this is legally incompatible.

You will have minimal trouble absorbing code from MIT, 3-clause BSD, and Apache into other projects with those same licenses. Or any other, really.

And while you can take code from MIT, BSD, and Apache into GPL project, taking GPL code into an MIT, BSD, and Apache project is only really possible if you now change the latter project's license to GPL.

So what's the license on a combination?

This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

Can you combine with proprietary licenses?

What if it's just libraries I depend on?

Unsorted (compatibility)

When do requirements apply?

Many requirements apply at the point you release, (re)sell or re-license the software (in binary and/or source form(verify)).

They generally do not apply to personal or hobby use unless that is explicitly stated (and there are legal limits to what may be limited) -- which, note, is also the case for copyrighted materials(verify).

Issues in combining software and licenses

This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

Source code licenses

Some comparison of copyleft and permissive licenses

This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.
GPLv3 AGPL LGPLv3 MPLv2 Apachev2 MIT (new) BSD public domain / unlicense
can copy/distribute without getting in trouble
(see also next two points)
under specific terms
(more than mentioning)
under basic terms
not necessarily, it turns out
Change must be distributed as source , also on network use is not a license, so
distributed code must have same license only for the library only for specifically MPL'd files

Liability and warranty disclaimer
Cannot use names to endorse

Patent provisions some[4]
(absent before v3)
(absent before v3)(verify)
some(verify) some(verify) some(verify)
Trademark provisions

could be monetized
If you get people to agree to give you money, sure - e.g. for support.
There is often nothing to limit nerdy people from getting a free copy elsewhere, though.

(there are other licenses that can prevent using free copies, or make it annoyingly hard)

Considers jurisdiction

GPLv3 AGPL LGPLv3 MPLv2 Apachev2 MIT (new) BSD public domain / unlicense

Explanation of summarizing one-liners

"Must distribute modified source"

This comes from a mindset central to (free and) open source:

"if you improve it, the benefits are for all, and those benefits must not be restricted".
Avoids a lot of double work and wheel reinvention.

For example, GPL, LGPL, AGPL, MPL does do this, whereas with BSD, X, Apache redistributing modifications is considered good style, but optional.

This usually applies when the result is distributed (released, and also often applies when internally distributed within an organisation). In that case, you can only demand the source when software with this restriction has been released, ...and not before then, or when someone is using for personal use.

In practice there are variations of how this applies, which are sometimes important. Consider:

  • Libraries: Consider for example the the difference between the GPL and LGPL.
While the GPL basically forces your entire project open, the LGPL makes libraries a separate thing:
if you simply use another's LGPL library it has no implications on your source around it
if you change that library it applies only to that library.
  • Services
some people, reading "on distribution of the software", got around having to provide source by providing the changed variant as an service instead of as downloadable software.
If you don't want that to happen, use something like the AGPL, which is mostly just GPL plus some 'on network use' wording.

"Any distribution → Same license" / "Distribution with this code included → Same license" / "Code that calls into this library → same license"

The "Must use same license" means the license says "no more, no less", mostly so that derivations cannot be stripped of the terms you set.

This is a central idea of copyleft.

There is a real question in "does this 'disclose with same license' apply..."

  • ...when you distribute software that happens to include said code in any way
  • ...only if you change it -- while using it unchanged (relevant for libraries) lets you treat it roughly as a distinctly licensed thing
this is roughly the distinction between GPL and LGPL - you can use LGPL libraries without having to open-source the thing that uses it, while derivations from the library must use the same license
  • ...even when you don't distribute it, but merely use it as a service?
the difference between the GPL and AGPL - the latter says 'network use is distribution'

Or, as the Mozilla Public License (MPL) solves it, its code may be included by closed/proprietary software, and only the MPL-licensed source must be distributed along(verify) (similar to LGPL, but per file rather than based on the distinction "library or not").(verify)

"Maintain Attribution and Disclaimer"

Well, just that.

This is true for almost all copyleft, as well as permissive licenses (for the latter it's most of what they do)

There are some exceptions, like the unlicense


It would be useful to also have

  • patent details
  • trademark details
  • no liability, no warranty (pretty much present in everything)

See also:

On patents

This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

On trademarks


While not an exact category, copyleft tends to mean "freer than copyright", and usually also "more restricted than permissive licenses'

GNU General Pulic License (GPL)


  • Include license
  • Maintain Attribution and Disclaimer
  • Disclose (distribute) modified source (and any source that uses)
  • Same license for derivative work


  • use commercially
  • modify
  • distribute


  • sublicense


  • "you improve it, you tell us" as a shared-cost continuous development cycle
  • Improvements are necessarily fed back to the community (...on release or sale)


  • Applicability to documents is sort of vague due to the code-specific wording. See GFDL instead.


  • Implicitly incompatible with various others
which makes it hard to combine in codebases where other licenses apply - any you may want to avoid GPL if you think that may apply in the future (see also next point)
  • The tiniest use of GPLed source forces everything around it to be open - potentially an entire project
LGPL is clearer on the point of how far it reaches when your software is a library
  • doesn't come into play when hosting things as a service
AGPL addresses that.

See also:

Version 2 and 3

Version 2 is still relatively current.

Version 3 updates 2 mostly in the point that it would extend to hardware (apparently, (verify)) and would have a provision there are no DRM-like systems (apparently, (verify)).

Similar/related to GPL


CeCILL is a GPL-compatible adaptation of the GPL to the French legal system.

There are also two variants:

  • CeCILL-B, which is rather like BSD, X11, MIT licenses
  • CeCILL-C, which is rather like LGPL

IBM Public License (IPL)

A variation of the GPL that:

  • moves liability from contributor to publisher/distributor.
  • terminates the license on patent disputes

Incompatible with (but generally very similar to) the GPL.

Related to, but not to be confused with IBM's Common Public License (CPL).

Common Public License (CPL)
  • Source license
  • Maintain Attribution and Disclaimer
  • Must Distribute Modified Source
  • Derivative work → Same license
  • Avoids contributors from sneaking in code with patents and then charing for it.
  • Future reviews could affect earlier software (also true for GPL, though(verify))

Eclipse Public License (EPL)
Affero GPL (AGPL)
This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

Roughly speaking, AGPL

takes GNU GPL's "when you distribute the software"
and makes it "when you distribute the software, or provide/use it as a service over a network."

Affero GPL is based on the observation that under GNU GPL, if you make alterations, then take the changed version and host it as a service yourself, that's not distributing the program, so you don't have to share your modifications.

And in a world where we

seem to care less and less about owning software, or even perpetual constant rights to use it,
just temporarily pay for the right to access,
'distributing' is much less a thing

If you avoid distributing, you bypass the entire intent of the sharing-back thing. If that reciprocity was the point of your license choice, this amounts to a loophole, that you may want to deal with.

The most relevant part, AGPL3 article 13[7], says "if you modify the Program, your modified version must prominently offer all users interacting with it remotely through a computer network [...] an opportunity to receive the Corresponding Source of your version [...] from a network server at no charge [...]"

See also:

  • EUPL, which seems to be a more compatible implementation of this idea (verify)
Server Side Public License (SSPL)
This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

A variant of the AGPL used by MongoDB and ElasticSearch,

Permissive licenses

BSD licenses (a.k.a. Berkeley licenses)

All vesions:


  • Include license
  • Maintain Attribution and Disclaimer
  • Disclose (distribute) modified source (and any source that uses)
  • Same license for derivative work - to sustain the attribution requirement.


  • (for coders) you can use this code without strong implications
  • (businesswise) this code can be used in proprietary programs you sell, requiring only attribution


  • (program/communitywise) vampirism is easy - anyone can use without doing someting in return, although this only really happens outside the (F)OSS communities.
The common examples are Microsoft's IP network stack being directly adapted from BSD's, and Apple's OS X which is strongly based in FreeBSD and mostly closed-source. No sharing, but you can argue both are positive results to end users.

For the case of binary distributions, these licenses will require copyright notices to be placed in the documentation.

Note that there are different versions of this license, and that similar (ISC, MIT) and derived (OpenBSD, NetBSD) licenses are often functionally equivalent to one of them. (See also: [8])

See also:

4-clause, "Original BSD License", "BSD license with advertising clause"

The original BSD license had four clauses. NetBSD still uses it. The clauses roughly require that:

  • Code (re)distributions must retain the copyright notice, the clauses, and the mentioned disclaimer
  • Binary (re)distributions must retain the copyright notice, the clauses, and all disclaimers
  • Advertisements mentioning this software must acknowledge its origin/contributors (what exactly to mention is stated in each specific license)
  • Names of copyright holders nor contributors may not be used in endorsements of (this/derived) software without permission.

Not GPL compatible because of the clause about advertisements.

The advertisement clause was initially intended for the BSD operating system itself. Once used elsewhere as-is, this means licenses were floating about with arbitrary mentions to the University of California, and many licenses with programmers' own names, which causes larger projects (e.g. and merging such software) to require any ads to mention dozens of names.

3-clause, "Modified BSD License", "New BSD License"

The "3-clause", "Modified BSD license" removes the third clause from the 4-clause version, making it:

  • Code (re)distributions must retain the copyright notice, the clauses, and the mentioned disclaimer
  • Binary (re)distributions must retain the copyright notice, the clauses, and all disclaimers
  • Names of copyright holders and contributors may not be used in endorsements of (this/derived) software without their permission.

GPL-compatible (verify)

2-clause, "Simplified BSD License"

FreeBSD and others use just the first two rules, i.e.:

  • Code (re)distributions must retain the copyright notice, the clauses, and the mentioned disclaimer
  • Binary (re)distributions must retain the copyright notice, the clauses, and all disclaimers

This is generally the assumed version when people say 'BSD license'.


MIT license / X11 license

  • Maintain Attribution and Disclaimer
  • Must Distribute Modified Source
  • "Same license for derivative work" (which implies only attribution) (verify)

Since the MIT license does not prohibit the use of the copyright holder's name in promotion, it's basically equivalent to the 2-clause variation of the BSD license

Note: When people say 'MIT license', they usually mean the license originally drafted for X11, probably the most significant license to come out of MIT, though of course not the only one used within MIT.

See also:

Apache licenses (ASL)

This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.
  • Maintain Attribution, Disclaimer
  • Must Distribute Modified Source
  • "Same license for derivative work" (verify)
apparently same license for unmodified, choice for modified?(verify)

The Apache Software License (ASL), usually just Apache License, is a permissive license similar to BSD and MIT style licenses, in that use is free of most restrictions and modifications may be kept secret and sold if one so chooses.

The main differences to BSD/MIT style are additions:

  • ASL is more more verbose and legally explicit about its intent
  • ASL2 mentions what happens when there are trademarks involved
"This License does not grant permission to use the trade names, trademarks, service marks, or product names of the Licensor"
  • it's also clearer about patents(verify)}
  • ASL2 adds some more explicit protective detail related to patents
"If You institute patent litigation against any entity ... then any patent licenses granted to You under this License for that Work shall terminate as of the date such litigation is filed."


  • Apache License 1 was GPL compatible (by mostly just being a rewritten BSD license), but
  • Apache License 2
    • became incomptible with GPLv2 (and GPLv1) because of the patent details - but this may be preferable to you
    • ...but seems compatible with GPLv3, in that Apache-licensed code can be used in GPL3 works. (verify)

See also:

Academic Free License (AFL)

  • Source license
  • Maintain Attribution and Disclaimer
  • Must Distribute Modified Source

Meant as a clarifying succession to Apache, MIT, BSD, and UoI/NCSA.

However, AFL-1.2 and AFL-2.1 are not GPL compatible. AFL-3.0 may be GPL compatible.


This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

Meant as a clarified version of the BSD/MIT licenses

Apparently GPL-compatible.

Python Software Foundation license

This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.
  • Source license
  • Maintain Attribution and Disclaimer
  • Must Distribute Modified Source

BSD-style - doesn't require source to stay open, but license must stay intact.


Note that an earlier version, the Python license, was not GPL-compatible (because of some mention of the laws of the State of Virginia) - though the name 'Python license' can also be used to refer to the newer version.

See also:

Weak copyleft

In terms of the restrictions a license imposes, there is plenty of room between permissive licenses (which have almost no restrictions) and strong copyleft (which tend to have a bunch)

Consider e.g. GPL says changes to the code means the entire program must be shared, and under the same license.

Weak copyleft like MPL2 basically says "share the part of the code you changed, under the same license"

GNU Lesser/Library Public License (LGPL)

  • Fairly specific to source
  • Maintain Attribution and Disclaimer
  • Must Distribute Modified Source (but not code that only uses)

LGPL is something like "GPL when you change, BSD-like when you use."

You have to publicise alterations to the library, but generally this just improves the library quality (may sometimes create a flurry of use and improvement) and rarely forces you to expose something you didn't want to.


  • Code can used in a (larger) project without having to open the entire project now or later


  • Allows legal reverse engineering (but so do most others)
  • LGPL-licensed software can be used in proprietary software. This is a purist view, noting this gives proprietary development an advantage over free software

In a semi-open world, LGPL (or one of the licenses like it) is a fairly good choice of both making your code useful for most everyone and making it low-implication for the most people.

A critical, pro-FOSS-and-anti-proprietary stance would note that you can be giving a proprietary project an edge by doing this since you can both use the library easily. The FSF takes this stance and suggests you use the GPL.

See also:

Mozilla Public License (MPL)

We now mostly talk about MPL2, rather than older versions.

MPL2 lies somewhere between permissive and strong copyleft, so is frequently called 'weak copyleft'.

Where e.g. GPL says changes to the code means the entire program must be shared, and under the same license, weak copyleft

Weak copyleft licenses like the Mozilla Public License 2.0 also require users to disclose their changes to the source code, but requires sharing of a narrower set of code. If an author reworks any of the original files, they have to release those updates when distributing the code and license them under the MPL.


European Union Public Licence (EUPL)

Open Source License (OSL)

  • Source license
  • Maintain Attribution and Disclaimer
  • Must Distribute Modified Source

(to check)

Not GPL-compatible.

Historical Permission Notice and Disclaimer (HPND)

This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

Some portions are optional for the licensor to choose, most of which (to introduce by comparison) move it around within the permissive (roughly 3-clause BSD equivalent to MIT equivalent) (verify).

The warranty disclaimer is also optional.


Considered deprecated.

Common Development and Distribution License (CDDL)

From Sun (can be seen as Sun Public License version 2; SPL was basically a revision of the Mozilla Public License).

Allows proprietary software in open source whole, apparently based on the idea that as an OS you couldn't do without closed-source drivers.


Artistic License

Python Software Foundation License ('Python License')

General / content / non-source licenses

Creative Commons (CC)

This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

Creative Commons refers to a set of licenses that allow you to choose the gradation of permissiveness.

The basic CC licenses are the possible combinations of the following requirements:

  • All: Maintain Attribution (and Disclaimer)
  • All: Name the original creator
  • Option: Share Alike: derivative work must be shared with same license
  • Option: Non-Commercial: work may not be used for commercial purposes
  • Option: No Derivative Works (only allowed to distribute unaltered copies of the work) OR derivative works allowed (but imply same license)

So there's a a bunch of combinations, like BY, BY-SA, BY-ND, BY-NC, BY-NC-SA, BY-NC-ND

Note that this carries very varied meaning. Say,

BY anb BY-SA are basically 'do whatever and have fun, just mention who originally made it'
ND means 'you cannot do anything with this'.
In terms of the commons or creation, this is just as controlling as copyright - you're just allowed to post it for free exposure.

As such, CC without mention of what kind means almost nothing.

CC has since created additional licenses, including:

  • Some specific cases, say,
    • attribution+noncommercial+noderivative for music sharing
    • license that have rather specific allowances
      • such as allowing sampling of the music but not reproduction as a whole
    • ...and more.

See also:

GNU Free Documentation License (FDL, GFDL)

The FDL (a.k.a. GFDL) can be seen as a variant of the GPL that replaces some terms that apply mostly to source code, and makes them about text in general instead.

The upsides include copylefting needs, and the ability to use other FDL'd content. FDL is used in various open content wikis, including Wikipedia.

The FDL also pays more attention to the more physical nature that documentation may take, considering books and such.

At the same time, one downside might be the burden introduced when you distribute more than 100 physical copies: you must include the FDL text and the source form for the content (digitally or physically). This is a problem for some formats, like pamphlets.

See also:


Gnu Simpler Free Documentation License (GSFDL)

A proposed variant of the GFDL, basically taking out the Cover Texts and Invariant Sections requirements for cases where that may be annoying.

Seems intended for manuals, textbooks and such, though could be used for any text.

See also:

FreeBSD Documentation License

A permissive license.

Rather like the BSD license, but for text.

See also:

Do What The Fuck You Want To Public License (WTFPL)

A no-nonsense variant on Public Domain (...without age conditions, question whether you can release something into PD, and such).

Free art license (Licence Art Libre)

This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

See also:

Apple's Common Documentation License

This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

Lesser General Public License For Linguistic Resources (LGPLLR)

This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

Meant to keep data for (computational) linguistics open for use, and keep its derivatives similarly open.

Design Science License (DSL)

A license meant for sharing scientific data, images and such rather than text or source.

Open Publication License (OPL)

May be used in free or non-free form, and has some restrictive options.(verify)).

From the Open Content Project, which now seems to recommend CC.

See also:

Open Content License

Somewhat restrictive, mostly monetary.

Arguably replaced by the Open Publication License.

See also:

Project Gutenberg License

This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

Refers to the overall license applying to Project Gutenberg - which mostly notes that public domain laws differ between countries, and explains copyright details that may apply to some resources -- note that PG has roughly two types of resources:

  • public domain resources
    • which technically come with the non-public-domain Project Gutenberg trademark and license. You either abide by these, or strip any reference to PG from the text (for a fully public domain resource)
    • some may have additional restrictions (verify)
  • copyrighted resources that authors gave to the project (mostly for ease of distribution), which are usually under more specific terms.

The exact details of a resource are explained in a summarizing blurb that comes with the text.

See also:

Can I change code license?

See also

Lists of licenses with comments:

Just lists:

Other discussions, comparisons and comments: