A file system is a method used by operating systems to organize and manage data stored on storage devices like hard drives and SSDs. It determines how files are named, stored, and retrieved, allowing users to easily access their data. Common file systems include NTFS, FAT32, and ext4, each with its own features and limitations. File systems also manage permissions and security, ensuring that only authorized users can access certain files. They keep track of where files are located on the disk, which helps in efficient data retrieval and storage. Overall, a file system is essential for maintaining order in digital data management.