directory

Filing cabinet' of a data-storage device (disk, CD, DVD) in which data (as files) is grouped and listed in a step-like (hierarchical) manner for allowing direct user access to any file. A directory is like a small database from which information is read much more often than it is written to. The beginning or 'top most' directory is called the 'root directory' which can, and often does, have lower level directories called 'sub-directories' which too can have their own sub-directories, and so on down to number of levels allowed by the operating system (OS). In all graphical user interface (GUI) based OSs (Linux, MacOS, Solaris, Windows), directories have meaningful names and are shown as 'folders' which can contain other nested folders (sub-directories). However, directories are 'logical' and not 'physical' subdivisions of a data storage media and any file in any directory may expand to fill all of the available storage space.