What's a Universal Windows app? and Guide to Universal Windows Platform (UWP) apps

A Universal Windows app is a Windows experience that is built upon the Universal Windows Platform (UWP), which was first introduced in Windows 8 as the Windows Runtime. At the core of Universal Windows apps is the idea that users want their experiences to be mobile across ALL their devices, and they want to use whatever device is most convenient or productive for the task at hand.

Windows 10 makes it easier to develop apps for the UWP with just one API set, one app package, and one store to reach all Windows 10 devices – PC, tablet, phone and more. It’s easier to support a number of screen sizes, and also a variety of interaction models, whether it be touch, mouse & keyboard, a game controller, or a pen.

read more: https://msdn.microsoft.com/en-us/library/windows/apps/xaml/dn726767.aspx

Guide to Universal Windows Platform (UWP) apps, learn about Universal Windows Platform (UWP) apps that can run across a wide variety of devices.

In this guide, you'll learn about:

• What a device family is, and how to decide which one to target.
• New UI controls and panels that allow you to adapt your UI to different device form factors.
• How to understand and control the API surface that is available to your app.

Windows 8 introduced the Windows Runtime (WinRT), which was an evolution of the Windows app model. It was intended to be a common application architecture.

When Windows Phone 8.1 became available, the Windows Runtime was aligned between Windows Phone 8.1 and Windows. This enabled developers to create Universal Windows 8 apps that target both Windows and Windows Phone using a shared codebase.

Windows 10 introduces the Universal Windows Platform (UWP), which further evolves the Windows Runtime model and brings it into the Windows 10 unified core. As part of the core, the UWP now provides a common app platform available on every device that runs Windows 10. With this evolution, apps that target the UWP can call not only the WinRT APIs that are common to all devices, but also APIs (including Win32 and .NET APIs) that are specific to the device family the app is running on. The UWP provides a guaranteed core API layer across devices. This means you can create a single app package that can be installed onto a wide range of devices. And, with that single app package, the Windows Store provides a unified distribution channel to reach all the device types your app can run on.