At long last, Microsoft held a press event on Thursday to officially reveal its new Windows 8 OS. Before diving into its flagship software upgrade, the company revealed its Windows RT software.

"Windows RT has been architected from the ground up for ARM processors," Microsoft's Steven Sinofsky said at the event.

Windows RT is a variant of Windows 8 that is compatible with devices that run on an ARM processor, the chips used in smartphones and tablets. Like Windows 8, it will not be able to run legacy programs and apps from previous Windows iterations. It will, however, be able to run any app available in the Windows Store.

Sinofsky announced that Windows RT will run new tocuh-enabled versions of Microsoft's Office 2013 suite, such as Microsoft Word and other programs. Internet Explorer 10 will also be touch optimzied for Windows RT.

Windows RT also supports more than 240 million existing hardware devices, according to Sinofsky. Many of these products will be able to connect to Windows RT out of the box.

Check back for more updates and new on Microsoft's press event; we'll be updating as more information is revealed.