The two main classifications of software are applications software and systems software. A wide variety of application software allows computer users to complete particular tasks. These include business, educational, graphic, multimedia and communication activities.
Application software is often purchased from vendors, although some is available free in the public domain. Systems software controls the computer and any associated devices. It coordinates the user, the application software and the computer hardware. Web servers, router operating systems and network devices are also run by the systems software. One kind of systems software is the operating system. It connects all hardware components to ensure they function together properly.