Konsep fail, direktori dan subdirektori.

file

Also referred to as simply a file system or filesystem. The system that an operating system or program uses to organize and keep track of files. For example, a hierarchical file system is one that uses directories to organize files into a tree structure.
Although the operating system provides its own file management system, you can buy separate file management systems. These systems interact smoothly with the operating system but provide more features, such as improved backup procedures and stricter file protection.

directory

(1) An organizational unit, or container, used to organize folders and files into a hierarchical structure. Directories contain bookkeeping information about files that are, figuratively speaking, beneath them in the hierarchy. You can think of a directory as a file cabinet that contains folders that contain files. Many graphical user interfaces use the term folder instead of directory.
Computer manuals often describe directories and file structures in terms of an inverted tree. The files and directories at any level are contained in the directory above them. To access a file, you may need to specify the names of all the directories above it. You do this by specifying a path.

The topmost directory in any file is called the root directory. A directory that is below another directory is called a subdirectory. A directory above a subdirectory is called the parent directory. Under DOS and Windows, the root directory is a back slash (\).

To read information from, or write information into, a directory, you must use an operating system command. You cannot directly edit directory files. For example, the DIR command in DOS reads a directory file and displays its contents.

(2) In networks, a database of network resources, such as e-mail addresses. See under directory service.

rujukan:http://www.webopedia.com/TERM/d/directory.html

subdirectory

A directory below another directory. Every directory except the root directory is a subdirectory. In Windows 95 and Windows/NT, subdirectories are called folders.