What is an operating system (OS)?

This article has been archived and is no longer updated by Apple.

Ever wonder what an "operating system" is? This concept is easier to understand than you may think.

The operating system

Imagine going to the symphony only to see the musicians sit quietly without sheet music or a conductor. That's like what your computer would do without an operating system, or "OS" -- it would turn on and do nothing useful. That's why all Macintosh computers come with a version of the "Mac OS" preinstalled. At the concept level, an OS is simply the software that controls your computer and tells it what to do. Your computer must have an OS installed before it can do anything useful or fun.

The current version of Mac OS is Mac OS X (pronounced "Mac O-S ten"). Earlier versions of Mac OS included Mac OS 9, Mac OS 8, System 7.5, and System 6. Major releases of Mac OS X include versions 10.0, 10.3, and 10.4. There are also updates (sometimes called "dot" releases) for each major release, such as versions 10.2.8 and 10.4.2. If you don't have Mac OS X and want to get it, be sure your computer can work with it, then visit this website for more information about upgrading.

Tip: Want to see what version of Mac OS you have? From the Apple menu (in the top-left corner of the screen), choose About This Mac.

Tip: An operating system includes thousands of files, many of which are protected so you can't accidentally remove them. The System folder in Mac OS X is an example. Each Macintosh comes with a backup copy of the Mac OS on system software CD or DVD.

An integral part of the Mac OS operating system is the Finder. To learn more about it, see "What is the Finder?"
Published Date: Oct 7, 2016