Software that initializes a disk. There are two formatting levels on a magnetic medium such as a hard disk or floppy disk. The low-level format initializes the disk surface by creating the physical tracks and storing sector identification in them as required by the particular drive technology used. Today's IDE and SCSI drives are all low-level formatted at the factory.

The high-level format creates the indexes used by the operating system's file system to keep track of data stored on the disk (see file system).

Floppy disk format programs perform both levels of formatting on the diskette at the same time. See Win Format a disk.