FAT is short for "File Allocation Table" and is used on Windows operating systems such as 95 and 98. When Windows 95 was first released it contained FAT16 but when Windows 98 was released it had advanced to using FAT32. Because Windows 98 uses FAT32 it could reduce the size of clusters and increase the bits used to address the clusters. This made hard disks run better and allowed larger hard disks to be supported.