What is a file system?
Why Interviewers Ask This
This question tests conceptual clarity. Interviewers want to hear a precise, confident definition before moving to more complex Operating Systems topics. It also reveals how well you can explain technical ideas to non-experts.
Answer
A file system is the method and data structure used by an operating system to control how data is stored and retrieved on storage devices. Without a file system, data would be one large blob with no way to organize or identify individual pieces. File system components: (1) Files: named collection of related data — the basic storage unit; (2) Directories (folders): hierarchical organization of files; (3) Metadata: attributes associated with files — name, size, creation time, modification time, permissions, owner; (4) Inodes: (Unix) data structures storing file metadata (not the name — that's in the directory); (5) Blocks/clusters: smallest addressable unit on disk (typically 4KB); (6) Free space management: track which blocks are available. Common file systems: ext4 (Linux — journaling, default); NTFS (Windows — journaling, permissions, encryption); FAT32 (universal, no journaling, 4GB file limit); exFAT (USB drives, no file size limit); APFS (Apple — copy-on-write, encryption, snapshots); ZFS (enterprise — integrity checks, RAID, snapshots); Btrfs (Linux — copy-on-write, snapshots). File system operations: create, open, read, write, seek, close, delete, rename, get attributes, set attributes, link, symlink. Virtual File System (VFS): abstraction layer in Linux that presents a uniform interface regardless of underlying file system type.
Pro Tip
Back up your answer with a specific project or situation. Saying 'In my last Operating Systems project, I used this when...' immediately makes your answer more credible and memorable.