MIME (Multipurpose Internet Mail Extensions) file types are an internet standard that’s used to describe the contents of various file formats. While the name MIME says ‘Mail’, it is also used for web pages.
The MIME type for HTML, for example, is:
MIME types are defined in HTML by the type attribute on links, objects, and script and style tags. The link above has a list of all MIME types by file extension. Computers also use file extensions to help the computer identify the file type. So if you have a file with an odd extension on your website, you can look up the MIME type on this list.