Internet media type

Internet Media Type (previously known as MIME type), and sometimes referred to as Content-Type (from the HTTP header it is often seen in) are the

type/subtype

specification of the type of content.

It is used in

• HTTP, most typically like
  Content-Type: text/plain; charset="UTF-8"
  (note: the charset part is optional but useful)

• each part of a MIME container

• and in various other places

The official list of MIME types is kept by IANA:

http://www.iana.org/assignments/media-types/

x-, vnd-, and such

something/x- are private subtypes

are not registered

(cannot be registered as exactly that. The registered form is often the same without the x-)

in theory everything non-registered should have this. Many but not all follow this.

Similarly, if you think up new type, it should also start with x- (to avoid conflicts with future standard types)

vnd are used when tied to vendor-specific and publicly available products, though that's a bit of a fuzzy distinction.

See also:

• http://stackoverflow.com/questions/312230/proper-mime-media-type-for-pdf-files

On charsets

HTTP and MIME allow the specification of character set on text/ types.

The value should be one registered at:

https://www.iana.org/assignments/character-sets/character-sets.xhtml

Charset names are considered case insensitive (see e.g. RFC 2616 clause 3.4

...though some browsers/UAs have been known to be case sensitive(verify)

See also:

• RFC 6657

See also

• http://en.wikipedia.org/wiki/Internet_media_type Internet media type
• RFC 2046
• http://www.iana.org/assignments/character-sets

"What's the mime type for..." (some common stuff)

This article/section is a stub — probably a pile of half-sorted notes, is not well-checked so may have incorrect bits. (Feel free to ignore, fix, or tell me)

Note that source code is in theory

application/

over

text/

whenever it settles its own character set (in specs or the document itself), such as in the case of javascript and XML.

See also RFC 4329 and this mention

• CSS

text/css

• Javascript

often

text/javascript

in practice

application/javascript

in theory (see note above)

Also seen:

application/x-javascript

• JSON

application/json

(see also RFC 4627)

(note: JSONP is Javascript code, not JSON)

• XML:

text/xml

in practice

application/xml

in theory (see note above)

• JPEG

image/jpeg

You also see:

image/jpg

(common mistake, not everything likes this)

image/pjpeg

for progressive JPEG - not standard (though apparently acceptable?)

• PDF:

application/pdf

RFC 3778

Also sometimes seen:

application/x-pdf

text/pdf

text/x-pdf

• RSS: RSS_and_Atom_notes#MIME_type

• MP3

audio/mpeg

according to RFC 3003 and HTML5[1]

A web search also shows a dozen others