"More than twenty years ago, Microsoft licensed its operating
system to IBM for inclusion with its new personal computer. PC-DOS,
as it was known in its IBM form, had many features and limitations,
but one feature that has grown in importance well beyond the realm
of the DOS world is its filesystem. The File Allocation Table (FAT)
filesystem, named after its key data structure, is perhaps the most
widely implemented filesystem in the history of computing.
"The FAT file system is used (or at least supported) by
everything from digital cameras to mainframe computers. This makes
FAT the filesystem of choice for cross-platform data exchange on
removable disks, and also an excellent way to exchange data between
OSes in a multi-boot configuration on a single computer..."