This document provides an introduction to Windows Store apps. It discusses that Windows Store apps are full screen, fit to the window, and require a closing gesture. They can be written in any .NET supported language and use WinJS. The document also summarizes that WinRT is a layer on the Windows 8 OS that uses some basic .NET classes and the Windows 8 UI, and only supports apps for the Windows Store. It provides examples of commonly used WinJS controls and reasons why apps may be activated or terminated.