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.
I realize that hardware vendors have long since turned their backs on Windows RT but the benefits of a malware free Windows world cannot be overstated. I remain unwilling to sacrifice the notion of the web for the peace and security of an app based ecosystem, however, the desktop is surely ripe for reinvention, and Windows RT is a good place to start.