A file name is a string of letters and numbers for user-oriented identification of a file. The file name is formalized according to the rules of the operating system and is recognized by the computer. It is used to identify a file by the system user and the program.
The operating systems support the spelling and different lengths of the file names. For example, Windows does not distinguish between upper and lower case letters, but Unix does. As far as the length is concerned, the file name is a maximum of eight characters long in MS- DOS, but several times that in the various Windows versions.