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  About MIME types

MIME (Multipurpose Internet Mail Extensions) is a mechanism for specifying and describing the format of Internet message bodies. It was primarily designed for e-mail, but MIME types are used also to identify the type of data in the HTTP protocol, the most widely used protocol on the World Wide Web.

For a browser like AWeb, the MIME type of a document determines whether the file should be displayed in the browser window, or be processed by some other program.

A MIME type consists of a type and a subtype. The type describes the major class of data, like text or image. The subtype is used for a subdivision of the major type into different formats, like GIF or JPEG images.

According to RFC 1521, the following official MIME types are defined:

TEXT/HTML
This is a document in the HTML hypertext format. Virtually all pages on the Web are in this format.

TEXT/PLAIN
This type is used for plain text documents (normally in ASCII).

APPLICATION/OCTET-STREAM
This describes a binary file. The file could be processed by some application. An example of this would be an LHA archive.

APPLICATION/POSTSCRIPT
The document is in PostScript format.

IMAGE/GIF
IMAGE/JPEG
These are images, in GIF and JPEG format.

AUDIO/BASIC
This type is used for audio data encoded using 8-bit ISDN mu-law [PCM].

VIDEO/MPEG
This is an animation in MPEG format.
In addition to these (and other) official types and subtypes, it is possible to define extension MIME types and subtypes. These should be prepended with "X-" to avoid collisions with future official MIME types.