Legacy Documentation: Version 5.6 (Go to current version)
Universal Windows 10 Applications: Getting Started
Windows Store: .NET Scripting Backend
Other Versions

Scripting Backends

Scripting backend is a framework that powers scripting in Unity. As of today, Unity supports three different scripting backends depending on target platform: Mono, .NET and IL2CPP. Windows Store, however, supports only two: .NET and IL2CPP.

You can switch between selected scripting backend in player settings:

Universal Windows 10 Applications: Getting Started
Windows Store: .NET Scripting Backend