Hierarchical file system

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In computing, a hierarchical file system is a file system that uses directories to organize files into a tree structure.^[1]

In a hierarchical file system, directories contain information about both files and other directories, called subdirectories which, in turn, can point to other subdirectories, and so on.^[2] This is organized as a tree structure, or hierarchy, generally portrayed with the root at the top. The root directory is the base of the hierarchy, and is usually stored at some fixed location on disk.

A hierarchical file system contrasts with a flat file system, where information about all files is stored in a single directory, and there are no subdirectories.

Almost all file systems today are hierarchical. What is referred to as a file system is a specific instance of a hierarchical system. For example, NTFS, HPFS, and ext4, all implement a hierarchical system with different features for buffering, file allocation, and file recovery.