Windows RT

Windows RT is a mobile operating system developed by Microsoft and released alongside Windows 8 on October 26, 2012. It is a version of Windows 8 or Windows 8.1 built for the 32-bit ARM architecture (ARMv7), designed to take advantage of the architecture's power efficiency to allow for longer battery life, to use system-on-chip (SoC) designs to allow for thinner devices and to provide a "reliable" experience over time. Unlike Windows 8, Windows RT was only available as preloaded software on devices specifically designed for the operating system by original equipment manufacturers (OEMs); Microsoft launched its own hardware running it, the Surface tablet, which was followed by Surface 2, although only five models running Windows RT were released by third-party OEMs throughout its lifetime.

In comparison to other mobile operating systems, Windows RT also supported 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. Some limitations it had compared to Windows 8 were that it could only execute software digitally signed by Microsoft, lacked certain developer-oriented features, and could not run applications designed for x86 processors, which were the main platform for Windows at the time. Windows RT 8.1 was released in 2013 as a free upgrade, featuring a number of improvements.