FAT is the acronym for File Allocation Table and it denotes the low-level organization of files on floppy and hard disks. The original FAT was a 16-bit file system that used 2 to the power 16 or 65536 clusters. The cluster size is equal to the hard disk capacity divided by the number of clusters, e.g. a hard disk with capacities larger than 0.5 or 1 GB have a cluster sizes of 16 KB and 32 KB, respectively. Every file stored on a hard disk uses a least one cluster and wastes on the average one half cluster of disk space. Therefore, FAT has a significant amount of wasted disk space. The original FAT is used by DOS, the original release of Windows 95 and optionally by Windows NT. It cannot handle hard disks larger than 2 GB.