An SMTP message structure that is the standard specification for the attachment of audio, video, image, and application programs to plain ASCII text messages.

A format originally developed for attaching sounds, images and other media files to electronic mail, but now also used with World Wide Web applications. A MIME mapping is a list of file extensions and the types of files they belong to. When the server sends an HTTP reply, it sends a type/subtype header according to the requested file's extension. A MIME type/subtype is an HTTP header sent with a reply that determines how a client will view or use the message. The MIME type tells the general type of document, such as image or application, and the subtype tells the specific type such as GIF or ZIP. [San Diego State University

An extension to Internet email which provides the ability to transfer non-textual data, such as graphics, audio and video.