All About OS X

Use this free lesson for OS X help navigating and using this Mac-based operating system.

What is OS X?

OS X (pronounced O-S ten) is an operating system designed by Apple. The operating system is what allows you to use a computer. OS X comes preloaded on all new Apple Macintosh computers (commonly known as Macs).

OS X makes it possible to complete all kinds of everyday tasks on your computer—for example, you can use OS X to browse the Internet, check your email, edit digital photos, listen to music, and play games.

screenshot of OS X

OS X is also used in some offices because it gives you access to productivity tools such as calendars, word processors, and spreadsheets.

screenshot of OS X

Earlier versions of Mac OS have been around since the mid-1980s. Apple released the first version of OS X in 2001. There have been many versions of OS X since then, but the most recent ones include High Sierra (to be released in 2017), Sierra (2016). El Capitan (2015), and Yosemite (2014).

In recent versions, Apple has rebranded OS X as macOS (for example, macOS High Sierra). However, the interface is still very similar, and for most purposes the terms OS X and macOS can be used interchangeably.

About this tutorial

This tutorial is designed to show you the absolute basics of using OS X on your Mac, including how to use the desktop, how to open different files and applications, and how to move and resize windows. The information in this tutorial will apply to most recent versions of OS X, including those mentioned above. However, once you've learned the basics, you may also want to review one of our version-specific OS X tutorials—just select the version of OS X that's installed on your Mac from the list below.