What technologies can I use to develop Windows 10 UWP applications?

Now that Windows 10 is here, as an application developer you might be interested in developing for the new Universal application platform, or UWP. Visual Studio is, quite naturally, the main development environment, but which technologies and languages can you use as a developer?

To summarize, Windows 10 UWP applications can be developed with three languages and two libraries. Firstly, you can choose from C#, Visual Basic .NET (VB.NET) and JavaScript/TypeScript. Secondly, you can either choose to build your user interfaces using the XAML language or using web technologies: HTML5 and CSS3 and the so-called WinJS UI library.

For more information, check out the "Developing Windows Applications" on MSDN.