Universal Windows Platform (UWP) is an application programming interface (API) created by Microsoft to develop universal applications that run on Windows 10, Windows 10 Mobile, Xbox One and HoloLens without the need to be re-written for each system.
Microsoft Developer Network (MSDN) provides information about UWP.
Here are books about UWP.
Building Apps For The Universal Windows Platform
Author: Ayan Chatterjee
Price: US $40
On sale @ Amazon.
Shop @ Apress.