Multimedia Internet Mail Extenstions
Internet Mail was originally specified in rfc 822, and could only convey 7 bit clean ascii (I.e. the top bit of every 8 bit byte was set or cleared at random or used for parity)
the MIME standard extends this, by defining a wrapper protocl (base64 encoding) plus a set of content descriptors
MIME is used for MM mail, bboards and WWW