What is a file system, and what does it do?

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A method used by operating systems to organize, store, name, and retrieve files on storage devices, defining how data is structured on the disk. A file system is the method and data structure that an operating system uses to organize, store, manage, name, and retrieve files on storage devices (hard drives, SSDs, USB drives, etc.). It defines how data is arranged on the disk, how files are named and located, and how metadata (file size, creation date, permissions) is tracked. Common file systems include NTFS (Windows), ext4 (Linux), APFS (macOS), and FAT32/exFAT (cross-platform, USB drives). The file system maintains a directory structure (folders/directories) that provides a hierarchical organization for files.

A physical filing cabinet is an analog metaphor that inspired the concept but is not a computer file system. Antivirus software scans for and removes malicious programs; it uses the file system but is not the file system itself. A text editor is an application for modifying text files, not the underlying system that organizes and stores those files on disk.

File systems are a core operating system concept on the DSST Computing and Information Technology exam. Students should understand how files are organized hierarchically in directories, common file system types and their features, the concept of file permissions (read, write, execute) and how they control access, path names (absolute vs. relative), and the difference between file deletion and actual data erasure on disk.

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