Hardware maintenance is the testing and cleaning of equipment.
Software maintenance is the updating of operating systems and application programs in order to add new functions and change data formats. It also includes fixing bugs and adapting the software to new hardware devices. See program maintenance
Information system maintenance is the routine updating of databases, such as adding or deleting employees and customers, as well as changing credit limits and product prices. See information system
Disk and file maintenance is the periodic reorganizing of disk files that have become fragmented due to continuous updating. See fragmentation
and file system