Computer Software
System software
Utility software

The functionality of the Operating System is extended by the use of utility software. Tasks performed by the various utility functions include:

• Backing up of data
• Power management
• Organisation of files (housekeeping)
• Anti-virus utilities
• Screen savers
• Recovery of deleted data
• Un-install programs.

Many utility functions are integrated into operating systems because they provide essential tasks for maintaining a reliable system, but additional utility programs are purchased separately as software packages and installed by the user or service provider.

Utility programs are activated by the user issuing a run or execute program command to the Operating System. However, some utility programs are loaded into main memory and executed automatically when the computer is first booted. A common example of this type of 'memory resident' utility is anti-virus software.