MIME Types
Common File Formats and Content-Types
Originally, the Simple Mail Transport Protocol (SMTP), used to send email messages, only allowed users to exchange ASCII text files. In 1991, Nathan Borenstein of Bellcore proposed to the Internet Engineering Task Force (IETF) that SMTP be extended so that Internet clients and servers could recognize and handle other types of data as well. Thus, MIME (Multi-Purpose Internet Mail Extensions), an extension of the original Internet email protocol, was born. MIME lets people exchange various types of files on the Internet including scripts, stylesheets, images, audio files, video files, programs, text files, etc.
Servers insert a MIME header that lists the types of files it is sending and can recognize at the beginning of any Web transmission. Clients use this header to select an appropriate "player" application for the type of data the header indicates. Some of these players are built into the Web client, (for example, most web browsers can "play" GIF, JPEG, and HTML files); other players usually have to be downloaded.
Some Common MIME Types
| Format | Content-Type |
|---|---|
| HTML | text/html |
| Text | text/plain |
| GIF | image/gif |
| JPEG | image/jpeg |
| PostScript | application/postscript |
| MPEG | video/mpeg |
| Form Data - POST method | application/x-www-form-urlencoded |
| Form Data - GET method | multipart/form-data |
| JavaScript | text/javascript |
| Cascading Style Sheet | text/css |
Copyright © 1997-2001 by Tina McDuffie