On the Windows side, this is the tool which supports Microsoft’s “universal app” strategy, allowing developers to build a single app for Windows desktop, tablet and mobile.
Just to clarify, Tim - you are talking about VS2015 ("the tool") and not the ASP.NET web framework you were talking about at the end of the previous paragraph?
That's kind of confusing on the first read-through, especially as the grammar points to the latter case which is er, utter nonsense.