An operating system is the most important software that runs on a computer. It manages the computers memory and processes, as well as all of its software and hardware. It also allows you to communicate with the computer without knowing how to speak the computers language.

An operating system has three main functions: 1) manage the computers resources, such as the central processing unit, memory, disk drives and printers. 2) establish a user interface and 3) execute and provide services for applications software.