Initially email consisted messages containing simple text written in English and expressed in ASCII. It cannot be used for languages other than English (such as French, German, Hebrew, Russian, Chinese, and Japanese). Also, it cannot be used to send binary files or video or audio data.

The basic idea of MIME (Multipurpose Internet Mail Extensions) is to add structure to the message body and define encoding rule for non- ASCII messages. MIME transforms non-ASCII data to ASCII data and vice-versa.

MIME defines five headers that can be added to the original e-mail header section to define the transformation parameters: