A file system is the underlying method an operating system uses to store, organize, and retrieve files on a disk or other storage device. It determines how data is structured into blocks, how directories are maintained, and how permissions are applied. File systems enable applications to create, read, write, and delete files in a predictable manner. Different file systems are optimized for performance, security, or reliability. They track metadata such as file size, timestamps, and access rights. A file system acts as the bridge between user level operations and low level hardware interactions. Every process relies on the file system to access the resources it needs.
how it works
When a program requests data, the file system translates logical paths into physical disk locations. It manages caching to speed up repeated reads and coordinates with the operating system scheduler. Some file systems support journaling, which protects against corruption by recording changes before applying them. Network file systems allow files to be shared across machines via protocols such as NFS or SMB. File systems differ widely, from simple FAT32 to advanced systems like ZFS or ext4. Understanding file systems is critical for debugging storage performance, disk failures, and permission issues.