The capacity of any disk is limited (e.g., 500 GB, 1TB etc.). Thus, to accommodate our new files, the space freed by deleted files is reused by the system by maintaining a free-space list.
We all save our files in the hard disk. To make the maximum out of the disk we space the files have to be stored in an efficient manner.
File management is another important function of an operating system. File management is necessary so that the operating system can map files onto physical devices