A media type (also known as MIME type and content type) is a two-part identifier for file formats and format contents transmitted on the Internet. The Internet Assigned Numbers Authority (IANA) is the official authority for the standardization and publication of these classifications. Media types were first defined in Request for Comments 2045 in November 1996, at which point they were named MIME (Multipurpose Internet Mail Extensions) types. They became known as media types when it became apparent that their usage had expanded to protocols which did not relate specifically to mail.