Windows RT

Windows RT is an edition of Windows 8 operating system designed for mobile devices that use 32-bit ARM architecture. Microsoft intended for devices with Windows RT to take advantage of the architecture's power efficiency to allow for longer battery life, to use system-on-chip designs to allow for thinner devices, and to provide a "reliable" experience over time. In comparison to other mobile operating systems, Windows RT also supports a relatively large number of existing USB peripherals and accessories, and includes a version of Microsoft Office 2013 optimized for ARM devices as pre-loaded software. However, while Windows RT inherits the appearance and functionality of Windows 8, it contains a number of limitations, which includes only being compatible with software obtained from Windows Store, and lacking certain enterprise-oriented features.

Due to the different architecture of ARM-based devices compared to x86 devices, Windows RT has software compatibility limitations. Although the operating system still provides the traditional Windows desktop environment alongside Windows 8's touch-oriented user interface, the only desktop applications officially supported by Windows RT are those that come with the operating system itself; such as File Explorer, Internet Explorer, and Office RT. Only Windows Runtime apps (obtained from Windows Store or sideloaded in enterprise environments) can be installed by users on Windows RT devices. Developers cannot port desktop applications to run on Windows RT, since Microsoft developers felt that they would not be properly optimized for the platform. As a consequence, Windows RT also does not support "new-experience enabled" web browsers: a special class of app used on Windows 8 that allows web browsers to bundle variants that can run in the Windows RT "modern-style user interface" and integrate with other apps, but still use Win32 code like desktop programs.

While Windows RT functions similarly to Windows 8, there are still some notable differences between the two platforms, primarily involving software and hardware compatibility. Julie Larson-Green, then executive vice president of the Devices and Studios group at Microsoft, explained that Windows RT was ultimately designed to provide a "closed, turnkey" user experience, "where it doesn't have all the flexibility of Windows, but it has the power of Office and then all the new style applications. So you could give it to your kid and he's not going to load it up with a bunch of toolbars accidentally out of Internet Explorer and then come to you later and say, 'why am I getting all these pop-ups?' It just isn't capable of doing that by design."