System software is closely related to, but distinct from operating system software. It is any computer software that provides the infrastructure over which programs can operate, i.e. it manages and controls computer hardware so that application software can perform. Operating systems, such as Microsoft Windows, Mac OS X or Linux, are prominent examples of system software.
System software is software that basically makes the computer work. Besides operating systems, other examples are anti-virus software, communication software and printer drivers. Without the system software the computer doesn't work. In contrast to system software, software that allows you to do things like create text documents, play games, listen to music, or surf the web is called application software.
In general application software are programs that enable the end-user to perform specific, productive tasks, such as word processing or image manipulation. System software performs tasks like transferring data from memory to disk, or rendering text onto a display device.
 Types of system software
System software can be classified as operating system, device drivers and utility software. An operating system creates an interface between user and the system hardware, while other system software will refine or allow greater interaction with the machine's hardware.
System software helps run the computer hardware and computer system. It includes operating systems, device drivers, diagnostic tools, servers, windowing systems, utilities, language translator, data communication programs, data management programs and more. The purpose of systems software is to insulate the applications programmer as much as possible from the details of the particular computer complex being used, especially memory and other hardware features, and such accessory devices as communications, printers, readers, displays, keyboards, etc.