Visual Studio 2015 includes several new features like Roslyn, which exposes the C# and VB.NET compilers as APIs. It allows building code analyzers and refactors directly into tools like the IDE. VS2015 also includes new C# language features enabled by Roslyn like null-propagating operators, auto-property initializers, and primary constructors. Refactoring tools have also been improved with light bulbs for quick actions and code previews. Code Lens allows seeing references and implementations directly in code.