<P> In keeping with Unix philosophy, Unix systems treat directories as a type of file . </P> <P> The name folder, presenting an analogy to the file folder used in offices, and used in a hierarchical file system design for the Electronic Recording Machine, Accounting (ERMA) Mark 1 published in 1958 as well as by Xerox Star, is used in almost all modern operating systems' desktop environments . Folders are often depicted with icons which visually resemble physical file folders . </P> <P> There is a difference between a directory, which is a file system concept, and the graphical user interface metaphor that is used to represent it (a folder). For example, Microsoft Windows uses the concept of special folders to help present the contents of the computer to the user in a fairly consistent way that frees the user from having to deal with absolute directory paths, which can vary between versions of Windows, and between individual installations . Many operating systems also have the concept of "smart folders" that reflect the results of a file system search or other operation . These folders do not represent a directory in the file hierarchy . Many email clients allow the creation of folders to organize email . These folders have no corresponding representation in the filesystem structure . </P> <P> If one is referring to a container of documents, the term folder is more appropriate . The term directory refers to the way a structured list of document files and folders is stored on the computer . The distinction can be due to the way a directory is accessed; on Unix systems, / usr / bin / is usually referred to as a directory when viewed in a command line console, but if accessed through a graphical file manager, users may sometimes call it a folder . </P>

What is the relationship between a folder and a subfolder