An Internet media type[1], originally called a MIME type after MIME and sometimes a Content-type after the name of a header in several protocols whose value is such a type, is a two-part identifier for file formats on the Internet. The identifiers were originally defined in RFC 2046 for use in e-mail sent through SMTP, but their use has expanded to other protocols such as HTTP, RTP and SIP.
A media type is composed of at least two parts: a type, a subtype, and one or more optional parameters. For example, subtypes of text type have an optional charset parameter that can be included to indicate the character encoding, and subtypes of multipart type often define a boundary between parts.
Types or subtypes that begin with x- are nonstandard[2] (they are not registered with IANA). Subtypes that begin with vnd. are vendor-specific; subtypes in the personal or vanity tree begin with prs..[3]
MIME is short for Multipurpose Internet Mail Extensions, a specification for formatting non-ASCII messages so that they can be sent over the Internet. Many e-mail clients now support MIME, which enables them to send and receive graphics, audio, and video files via the Internet mail system. In addition, MIME supports messages in character sets other than ASCII.
There are many predefined MIME types, such as GIF graphics files and PostScript files. It is also possible to define your own MIME types.
In addition to e-mail applications, Web browsers also support various MIME types. This enables the browser to display or output files that are not in HTML format.
MIME was defined in 1992 by the Internet Engineering Task Force (IETF). A new version, called S/MIME, supports encrypted messages.
[edit] List of common media types
IANA manages a registry of media types and character encodings. The organization makes a list available to the public through the Web. Some of the more notable media types used on the Web are listed below:
- Type
application: Multipurpose files application/x-www-form-urlencoded Form Encoded Data XDapplication/EDI-X12: EDI X12 data; Defined in RFC 1767application/EDIFACT: EDI EDIFACT data; Defined in RFC 1767application/javascript: JavaScript; Defined in RFC 4329 but not accepted in IE 8 or earlierapplication/octet-stream: Arbitrary binary data[4]. Generally speaking this type identifies files that are not associated with a specific application. Contrary to past assumptions by software packages such as Apache this is not a type that should be applied to unknown files. In such a case, a server or application should not indicate a content type, as it may be incorrect, but rather, should omit the type in order to allow the recipient to guess the type.[5]application/ogg: Ogg, a multimedia bitstream container format; Defined in RFC 5334application/pdf: Portable Document Format, PDF has been in use for document exchange on the Internet since 1993; Defined in RFC 3778application/xhtml+xml: XHTML; Defined by RFC 3236application/xml-dtd: DTD files; Defined by RFC 3023application/json: JavaScript Object Notation JSON; Defined in RFC 4627application/zip: ZIP archive files; Registered[6]
- Type
audio: Audio - Type
image - Type
message - Type
model: 3D models - Type
multipart: Archives and other objects made of more than one part - Type
text: Human-readable text and source code - Type
video: Video
- Type
vnd: Vendor Specific Files [10]
- Type
x: Non-standard files[10] application/x-dvi: Digital Video files in DVI formatapplication/x-httpd-php: PHP filesapplication/x-httpd-php-source: PHP source filesapplication/x-latex: LaTeX filesapplication/x-shockwave-flash: Adobe Flash files; Documented in Adobe TechNote tn_4151 and Adobe TechNote tn_16509application/x-stuffit: StuffIt archive filesapplication/x-rar-compressed: RAR archive filesapplication/x-tar: Tarball files
- Type
x-pkcs: PKCS standard files application/x-pkcs12: p12 filesapplication/x-pkcs12: pfx filesapplication/x-pkcs7-certificates: p7b filesapplication/x-pkcs7-certificates: spc filesapplication/x-pkcs7-certreqresp: p7r filesapplication/x-pkcs7-mime: p7c filesapplication/x-pkcs7-mime: p7m filesapplication/x-pkcs7-signature: p7s files
[edit] References
- ^ "Internet Media Type registration, consistency of use". W3C. 2002-06-03. http://www.w3.org/2001/tag/2002/0129-mime. Retrieved 2006-11-29.
- ^ Freed, N. (November 1996). "RFC 2045 - Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies". IETF. http://tools.ietf.org/html/rfc2045#section-6.3. Retrieved 2006-11-29.
- ^ Freed, N.; Klensin, J. (December 2005). "RFC 4288 - Media Type Specifications and Registration Procedures". IETF. http://tools.ietf.org/html/rfc4288#section-3.2. Retrieved 2008-06-14.
- ^ http://tools.ietf.org/html/rfc2046
- ^ http://www.w3.org/Protocols/rfc2616/rfc2616-sec7.html#sec7.2.1
- ^ http://www.iana.org/assignments/media-types/application/zip
- ^ http://www.iana.org/assignments/media-types/image/png
- ^ http://www.iana.org/assignments/media-types/image/vnd.microsoft.icon
- ^ http://www.iana.org/assignments/media-types/video/quicktime
- ^ a b "ContentType". http://www.asptutorial.info/sscript/ContentType.asp. Retrieved 2008-04-24.
- ^ http://www.iana.org/assignments/media-types/application/vnd.oasis.opendocument.text
- ^ http://www.iana.org/assignments/media-types/application/vnd.oasis.opendocument.spreadsheet
- ^ http://www.iana.org/assignments/media-types/application/vnd.oasis.opendocument.presentation
- ^ http://www.iana.org/assignments/media-types/application/vnd.oasis.opendocument.graphics
[edit] See also
[edit] External links
