When it comes to computers, data is stored in files. When you run a program, MS-DOS processes the data stored in the file and passes it to the system. In MS-DOS a file can be any size, however the file name is more restricted, it can only have a maximum length of 8 characters plus 3 for the extension.
Furthermore, the files can only contain the following characters:
Thus filenames must not contain:
Also, the cannot contain any of the following list of reserved names:
A hard drive can contain several thousands of files. However, the more files there are, the more difficult it is to manage them: this is when we need to store them in directories. In MS-DOS, directory names are also subject to the same name restrictions as files.