MIME is short for Multipurpose Internet Mail Extensions. It is a specification for formatting non-ASCII messages so that they can be sent over the Internet. While originally intended to support e-mail transfer of multi-resource HTML multimedia documents, MIME packages are now commonly employed using other transfer protocols. A MIME-encoded package contains a root resource (object) as well as other resources linked to it via URIs. These other resources may be required to display multimedia within the document that can include items such as graphics, audio, and video files.
MIME was defined in 1992 by the Internet Engineering Task Force (IETF). A new version, called S/MIME now supports encrypted messages.