Tree structured directories:

This is the main common directory structure. The tree has a root directory as well as every file in the system has a unique path name. A directory or subdirectory includes a set of files or subdirectories. A directory is basically a file except it is treated in a special way. All directories have the similar internal format. One bit in every directory entry defines the entry as a file (0) or as a subdirectory (1). Special system calls are accustomed to create and delete directories.

This structure permits users to create their own files or subdirectories and arrange them accordingly. Users are able to be as well allowed to access the files of other users as well.

                                                          The tree structured directory structure