Yes. A directory can be called a file and, in most implementations, under the wraps, it is a file, but it is not a file that an ordinary user can access. It is the responsibility of the file system code in the operating system. Unless you are writing code that manages file systems, it is best to think of a directory as a directory and to use the API provided to access it.
The /, or root directory.
The df utility displays a list of the directory hierarchies available on the file system. NFS is the file system type.
An inode is a data structure in a Unix-style file system that stores information about a file or directory, such as its permissions, ownership, size, and location on the disk. It also contains pointers to the actual data blocks of the file. Each file on the system is represented by an inode.
Windows 2000 Active Directory data store, the actual database file, is %SystemRoot%\ntds\NTDS.DIT
file manager
Information about a directory entry, Information about a set of changes to a directory entry
There's no particular requirements on how deep a directory needs to be or should be. The directory can be any depth, subject to file system limitations.
1. Directory files are the system file and can be not change or modified. The ordinary file are the one user create and it can be modified and changed .
A directory is a logical grouping of files. By maintaining several directories the file manager can permit the same file name to be used in separate directories to refer to independent copies of the same file or completely different files. The contents of a directory - a list of file names and their associated information - are stored in a special file called a directory file which is assigned a file name which distinguishes it from non-directory files. By allowing directory file names to appear alongside non-directory file names in a directory, the file manager is able to link separate directories hierarchically as shown in figure 1. The directory at the top of the structure is given the special name, ROOT because the hierarchical structure resembles an upside-down tree. The directories below the root directory are known as subdirectories. by earnie
root directory
File System.