The UNIX file system is organized as a hierarchical tree . A directory is a listing of files and other directories.
Directories help keep the masses of files organized in a meaningful way.
A file contains information or is a special file . Ordinary files are used to store data, code or text. A program can get inputs from, and send outputs to an ordinary file. A program can get inputs from, and send outputs to a special file. An application program can put its outputs into an ordinary file.