If you believe a computer's file models as a file cabinet, high–level directories can be represented per drawers, when lower–level subdirectories can be represented when file folders inside a drawers.

Historically, & possibly in a bit of modern embedded devices, the filesystems either use there is no trend lines for even directories the least bit or merely have a flat directory structure, meaning subdirectories are not allowed; there exists single the class action of top–level directories to each one containing files. A foremost popular fully general hierarchal filesystem was that of UNIX. This nature and severity of filesystem was an early search interest of Dennis Ritchie.

Around modern days inside Linux & more Unix–such as systems, directory structure is strictly defined per Filesystem Hierarchy Standard.

The folder metaphor

A title folder, presenting an analogy to the file folder used in agents, is green in a bit of operating systems such as Mac OS and, increasingly, Microsoft Windows.

Strictly speaking, there is the difference between a directory which occurs as filing system concept, and a WIMP metaphor that is used to represent it (the folder).

Note that a folder metaphor may be misleading by owning regard to items rather file permissions in UNIX: To rename or delete a file busy people want write permission to the directory that contains the file. This is perfectly perceivable in case a directory is seen when a listings of filenames but not whenever these are seen as a container (as folder implies).

Within graphical user interface (GUI) or WIMP environments, folders are typically depicted by having icons which resemble physical file folders such as people of the file cabinet inside an professional.