File systems define the structure of files and directories. A few file systems have hierarchical directory structure and have unlimited depth. Some File systems have a limit on the depth of the directory structure.
In most File systems directory structure is fixed and read-only. It means that you can create directories or folders and file, and perform operations like modifying and deleting the directory or folder inside the directory or folder. The file system will not allow you to modify the structure of the directory or folder.
