A file system is a method used by operating systems to organize and manage data on storage devices like hard drives and SSDs. It determines how files are named, stored, and retrieved, allowing users to access their data efficiently. Common file systems include NTFS, FAT32, and ext4, each with unique features and limitations. File systems also handle permissions and security, ensuring that only authorized users can access certain files. They maintain the structure of directories and subdirectories, making it easier to navigate and manage large amounts of data. Overall, file systems are essential for effective data management in computing.