System software is software that controls a computer and runs applications on it, providing the environment for application software. Application software is the software in application programs—also called computer programs and software programs—that allow the user to perform tasks, play games, listen to music, and otherwise make use of the computer. System software is a collection of programs, and each type has a number of component parts, most notably the operating system (OS). Also included in system software are utilities, device drivers, and language translators.

Utilities include a variety of specialized programs that can be applied across application programs. Basic utilities include trouble-shooting and/or diagnostic program. Other utilities may include backup programs, file compression, uninstall, and antivirus programs. Device drivers are needed for every peripheral connected to the computer, from the mouse and keyboard to the printer and/or scanner. Device drivers for basic components — like the mouse and keyboard — are included in the system, while others may be supplied by the peripheral manufacturer.

System software differs from application software in several ways besides in general purpose. First, it is necessary, whereas any particular example of application software is optional. Second, it is complete in that no computer needs to have more than one type of system software on it at any given time, although some set-ups allow for multiple types of system software to be installed. Applications, on the other hand, are generally placed on a computer in large numbers. In addition, system software is independent and requires no application software to run, whereas application software cannot run in the absence of system software.

Although it has multiple components, system software is generally typed by the operating system. DOS was an early operating system that is not in much use anymore. The main operating systems are Windows®, Apple®, Linux®, and Unix®. Each operating system has at least several sub-types, including Windows® XP, Windows® 7 Windows® Vista®, Apple® Mac® OS X, etc.

Newer Macintosh® Intel® computers are capable of running two different types of system software: Apple® software and Windows®, Linux®, or other software. There are two ways that they can include Windows® software. One way is through software known as Boot Camp®, which allows the user to choose the preferred software at startup. The other is through Parallels® desktop software which allows two operating systems to be accessed simultaneously.