Abbreviation from the file allocation table
A FAT / FAT32 is an option for an operating system to keep an overview of the data stored on a data carrier. FAT32 stands for a more modern FAT variant, which is based on 32-bit. The FAT is often compared to a table of contents of a very diverse book. A comparison of the Internet without search engines comes closer. In other words, if the FAT is destroyed, the data is still available, but the operating system can no longer access it.
Trivia: A hacker once said: "A file system with destroyed FAT is like a 10,000 piece puzzle with the motif meadow green".