iOS is a mobile device operating system created and developed by Apple exclusively for their own hardware. It is the operating system that powers most of Apple’s mobile devices including the iPhone, iPad and iPod Touch. iOS is the second most popular mobile device operating system globally after Android.
Like modern desktop operating systems, iOS uses a graphical user interface (GUI). However, since it is a mobile operating system, it is designed around touchscreen input, rather than a keyboard and mouse. For example, apps can be opened by a single tap, rather than a double-click and different screens can be viewed by swiping a finger across the screen, rather than clicking on open windows.
Since iOS is designed to be simple and easy to use, it does not include several features found in a traditional operating system. For example, you cannot manage files and folders like you can in Mac OS X or Windows. Besides there is only limited access to iOS system settings. Instead of modifying application preferences from within each program, most settings need to be adjusted in the Settings app. Apart from that, while you can run multiple programs at once, you can only view one open program at a time.