Windows 8 RT (codenamed Windows on ARM) - is a special version of the Windows 8 operating system designed to run on mobile devices utilizing the ARM architecture, such as tablets. Unlike Windows 8, Windows RT is only distributed as a pre-loaded operating system on devices produced by participating OEMs. Windows RT officially launched alongside Windows 8 on October 26, 2012 with the release of several Windows RT-powered tablets by various manufacturers, along with an RT version of Surface, the first ever Windows device manufactured and sold directly by Microsoft.
While it lacks certain features and compatibility in comparison to Windows 8 (which runs only on devices with Intel-compatible processors), Microsoft aimed for Windows RT devices to take advantage of the ARM platform’s power efficiency (allowing for longer battery life), using system-on-chips to allow for thinner hardware designs, the new Windows Store platform for touch-optimized apps, and providing a reliable experience over time. Unlike other variants of Windows, the operating system also ships with a special edition of Office 2013 as pre-loaded software. Due to these differences, Windows RT is more comparable to a mobile operating system such as iOS than other editions of Windows.
Windows RT was released to mixed reactions from various outlets and critics. Some felt that Windows RT devices had advantages over other mobile platforms (such as iOS or Android) due to its bundled Office applications and the ability to use a wider variety of USB peripherals and accessories. However, concerns were also raised surrounding its lack of compatibility with legacy applications and other functions, and possible confusion for consumers between Windows RT devices and those running 8 due to these differences.