A Multipurpose Internet Mail Extensions (MIME) type is a standard that indicates the nature and format of a document, file, or assortment of bytes. It is defined and standardized in IETF RFC 6838.
The Internet Assigned Numbers Authority (IANA) is responsible for all official MIME types, and you can find the most up-to-date and complete list at their Media Types page.
参考：https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/MIME_Types