This document summarizes application development tools and platforms. It outlines the release history of Visual Studio 2013 and updates, how Windows Runtime apps can be developed for both Windows and Windows Phone using common APIs and languages. It also describes new features in Windows Phone 8.1 like universal app templates and the ability to target both Windows and Windows Phone from a single project. The document concludes by thanking the reader and providing a link to the author's blog for more information.