Windows RT 8.1 is a Windows-based operating system that's optimized for thin and light PCs that have extended battery life and are designed for life on the go. Windows RT 8.1 only runs built-in apps or apps that you download from the Windows Store. Windows Update automatically keeps your PC up to date and Windows Defender provides up-to-date virus and malware protection.
How do I get Windows RT 8.1?
If you already have a PC or tablet that came with Windows RT pre-installed, then you can get the free update to Windows RT 8.1 from the Windows Store. You can only install Windows RT 8.1 on PCs or tablets that are already running Windows RT. You can buy a Windows RT PC at retail stores in some locations or check out some recommended Windows RT PCs.