The FAT File System, short for File Allocation Table, is a simple file system used for organizing and managing files on storage devices like hard drives and USB flash drives. It keeps track of where files are stored on the disk by using a table that maps the locations of file clusters, making it easy to read and write data. Originally developed in the late 1970s by Microsoft, FAT has evolved through several versions, including FAT12, FAT16, and FAT32. It is widely compatible with various operating systems, making it a popular choice for removable storage and embedded systems due to its straightforward structure and low overhead.