A table containing the structure of a file system on a computer, developed for MS-DOS. A FAT resides on a partition near the start and is a linked list that stores the logical order of the partition’s clusters, or small blocks of contiguous disk space. A file is stored in a chain of clusters, which are not necessarily adjacent to each other, with part of the last cluster for each file remaining empty and thus wasted. Each entry in the FAT contains the location of the next logical cluster. The FAT size relates to the number of bits used to address the clusters, e.g. 16, 32 bits. A larger size allows for smaller clusters to be used for a given partition size, resulting in less wasted space. Typically, two identical copies of the FAT are stored to help prevent accidental loss of data.