Apache AddType directive
It is the base module. mod_mime is the name of the module. This directive is legal in the server config, virtual host, directory, .htaccess server's configuration files.
The syntax is
AddType MIME-type extension [extension] ...
AddType image/gif .gif
Here the AddType maps the given filename extensions to the specified content type. MIME-type refers the MIME type(i.e., .gif) to use for filenames containing extension. This directive can be used to add mappings not listed in the MIME types file i.e., instead of .gif we can give anything like .dfdf but the image file extension should also end with the same extension. The extension argument is case-insensitive, and can be specified with or without a leading dot.