GNOME provides several modules that add extra functionality to the filesystem provided by the OS.
MIME is an industry standardized way of specifying the format and nature of a piece of information. It does so by providing an extendable list of types that can be associated with the information. GNOME has support for determining the MIME type of a file, in both a fast manner, and a more accurate, but slower fashion. The fast manner uses a regular expression on the filename to quickly try to determine the type. The slow fashion will read through the contents of the file and try to determine the type by magic.
The virtual filesystem, GnomeVFS, is an abstraction that allows applications to access different types of filesystems in a consistent fashion. It allows uniform access to files in your local filesystem, FTP sites, RPM packages, compressed archives and a lot of other sources, including digital cameras.
GnomeVFS provides transparent access to data methods and number of convenience libraries for processing URIs, detecting the MIME type of files an even figuring out which applications or components to launch to view a file or what icon to use.
You can extend GnomeVFS through modules in an easy manner. A GnomeVFS module provides special methods for a particular filesystem. It can for instance be used to access your portable Ogg Vorbis or FLAC player.