MIME

The Multipurpose Internet Mail Extensions (MIME) standard is defined in RCF 2045.
It was originally developed as a way to add (binary) attachments to what was at the time only plain-text email.
It has become a widely used technique for describing a file's content.
It supports almost a hundred predefined types of content.
Content types have a type, and a subtype. The type give a general idea of what the data represents (e.g., a picture, a video, a movie), which the subtype specifies the specific encoding (e.g., gif, jpeg, mpeg). Some examples are:
- text/html
- text/plain
- image/gif
- image/jpeg
MIME also allows the user to define non-standard types, by prefixing them with an x-
- application/x-framemaker
- audio/x-wav