Stands for "Virtual File Allocation Table."
VFAT is an extension to the FAT16 and FAT32 file systems that adds support for long file names. VFAT extends the FAT file systems but does not break backward compatibility. Operating systems that support it (like Windows 95 and later) can use long file names, while ones that don't (like MS-DOS and Windows 3.1) will see short, truncated names when viewing the same volume.
VFAT was introduced in Windows 95 to add support for long file names as part of an effort to make computers more user-friendly. The FAT16 file system used in DOS and Windows operating systems was limited to 8.3 file names — 8 characters with a file extension of 3 letters — but VFAT allowed file names up to 255 characters, including spaces, commas, multiple periods, and some other extended characters.
VFAT works by creating separate entries in a directory for the long file name and for a shortened 8.3 version. The long file name entry is formatted in a way that older operating systems will ignore in favor of the 8.3 file name. For example, a file with the long file name Audrey's Birthday Party.jpg will be shortened to AUDREY~1.JPG when viewed in an operating system that does not support VFAT.
NOTE: While the FAT32 file system does not support long file names as part of the specification, every operating system that supports it also supports VFAT. Therefore, someone using a FAT32 volume can expect long file name support.