iOS (pronounced "eye-oh-es") is Apple's mobile operating system that runs on the iPhone, iPad, and the iPod touch. It has a graphical user interface (GUI) that is optimized for touchscreen devices. For example, the iOS home screen displays several icons, which are arranged in a static grid. Each application or "app" can be opened by simply tapping the the icon, rather than double-clicking the icon, like a desktop OS.

iOS includes several apps, such as Safari (for web browsing), Mail (for email), Messages (for text messaging), and Music (for playing songs). It also supports third party apps developed by other software developers. These apps can be downloaded from Apple's App Store either directly from an iOS device or through iTunes on a Mac or PC. Unlike Google's Android operating system, iOS does not support the installation of apps from outside the official app store.

Like OS X, Apple focused on making iOS intuitive and easy-to-use. However, because it is designed specifically for mobile devices, iOS lacks the advanced features of a desktop OS. For example, iOS does not include a file manager or a means to navigate the file system. Additionally, iOS apps are often simplified and lack the features of their desktop counterparts. While iOS apps may not have the advanced capabilities of desktop applications, they make it easy to perform common tasks while on-the-go.

Updated: September 7, 2013

Definition from the PC Glossary