FS, or File System, is a method used by operating systems to manage and organize data on storage devices like hard drives and SSDs. It determines how data is stored, retrieved, and organized, allowing users to create, delete, and modify files and directories efficiently. Different types of FS exist, such as NTFS for Windows, HFS+ for macOS, and ext4 for Linux. Each has its own features and advantages, such as support for large files, security permissions, and data recovery options. Understanding FS is essential for effective data management and system performance.