A File System in Linux is a method for organizing and storing files and directories on a storage device, such as a hard drive or SSD. Linux supports various file systems, each with its own features and performance characteristics. Common Linux file systems include ext4 (widely used for general purposes due to its reliability and performance), XFS (known for handling large files and parallel I/O), Btrfs (offering advanced features like snapshots and data compression), and FAT32/NTFS (for compatibility with Windows systems). The file system determines how data is stored, accessed, and managed on the disk, including permissions, file attributes, and directory structures.