MIME is an abbreviation for "Multipurpose Internet Mail Extensions". At the start, email was intended to transport for textual message only and later added attachments etc. These attachments include different files of various formats like images, text files, video and audio etc. To name these extra attachments MIME was introduced. Browsers used to quote MIME types that their versions support. MIME describes the type of data the file contains.
A MIME type nomenclature includes a type and subtype separated by a forward slash. For example, a popular one is text/html. Here text is called type and html is known as subtype. A type may have various subtypes. A type groups files of similar nature like text/plain and text/css (Cascading Style Sheet) and text/richtext etc. List of popular MIME types is given at the end.
Sometimes, a MIME type comes with an optional character encoding also as follows as used in Servlets.
Here, the MIME type also describes the charset to interpret the data.
Some more Definitions
We know, the MIME types were originally developed to describe the Internet mail attachments. But later used by different technologies to inform the type of data being transported between them. For example, Servlets use MIME type (say, text/html) passed as parameter to response.setContentType("text/html") method to informs the client's browser of how data to be interpreted or displayed that will be sent by the server. To give good meaning for the wide usage of MIME, a new word is coined as "Internet Media Type". As on today, practically both MIME and IMT are one and the same.
The MIME types of governed by Internet Assigned Numbers Authority (IANA).
Some MIME types are used in public not registered with IANA. These are non-standard and sometimes specific for a particular vendor software. Examples
MIME describes the content type of the data sent by a server-side Web server to a client-side Web browser. This is used in HTTP protocol supported Servlets as response.setContentType("text/html"), known as header information.
application/postscript, application/msword, application/octet-stream, application/pdf, application/rtf, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/x-iphone, application/zip, audio/mpeg, audio/x-wav, image/gif, image/ief, image/jpeg, video/mpeg.