FAT16
The 16-bit version of the File Allocation Table (FAT) file systemhereafter FAT16was first used with DOS back when I was in parachute pants (that would be 1981). FAT16 divides the space on a fixed disk into 65,536 (which is 16 bits' worth, or 216) storage locations, and each location is assigned a number. The storage locations are also known as clusters. A cluster is the smallest unit of storage space on a FAT partition. A cluster can be allocated for a single file only, even if the file does not use up all the storage space. Also, a cluster can store just a part of a larger file.
