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 — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

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 instead, not JSON data)

• YAML - didn't have one for a long long time, so don't assume

application/yaml since 2024 - see RFC 9512

older things may use application/x-yaml, text/yaml(verify), or others

• 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?)

• PNG

image/png

• GIF

image/gif

• 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

• 'arbitrary binary data' (quoth e.g. RFC 2046)

application/octet-stream