System software is software designed to provide a platform for other software. Examples of system software include operating systems (OS) (like macOS, Linux, Android and Microsoft Windows), computational science software, game engines, search engines, industrial automation, and software as a service applications.

Application software is software that allows users to do user-oriented tasks such as create text documents, play or develop games, create presentations, listen to music, draw pictures or browse the web.

In the late 1940s, the early days of computing, most application software was custom-written by computer users to fit their specific hardware and requirements. System software was usually supplied by the manufacturer of the computer hardware and was intended to be used by most or all users of that system.

Many operating systems come pre-packaged with basic application software. Such software is not considered system software when it can be uninstalled without affecting the functioning of other software. Examples of such software are games and simple editing tools supplied with Microsoft Windows, or software development toolchains supplied with many Linux distributions.

Some of the grayer areas between system and application software are web browsers integrated deeply into the operating system such as Internet Explorer in some versions of Microsoft Windows, or ChromeOS and where the browser functions as the only user interface and the only way to run programs (and other web browsers can not be installed in their place).

Cloud-based software is another example of systems software, providing services to a software client (usually a web browser or a JavaScript application running in the web browser), not to the user directly. It is developed using system programming methodologies and systems programming languages.