What Is an Operating System?

By Faithe Wempen

An operating system (OS) is software that starts up a computer and keeps it running and responding to your commands. Operating systems have several important jobs. An operating system

  • Runs applications (useful programs like word processors, calculators, and so on) and enables you to interact with them.

  • Creates and maintains the user interface that you see onscreen, such as the icons you click and the dialog boxes you see.

  • Controls and manages the file storage system, so you can save and open data files in your applications and manage the files that run your applications.

  • Communicates with the hardware, giving it instructions to accomplish the tasks you request, such as printing your work.

Don’t look to the operating system for fun or productivity — that’s not its job. For example, you can’t use it to produce a newsletter, send an email, draw a picture, or look something up online. However, the operating system contributes to all those activities because it enables applications to run that can do all those things.