Where can I find source code for .net CLR and C#?

Question

Is the source code for Microsoft .net CLR and C# open? If yes, where can I download/browse it?

Answer 1

Part of .NET Core is now open-source, starting with .NET Core 5.0.
Here is the project site: http://www.dotnetfoundation.org/netcore5
Here is the code: https://github.com/dotnet/corefx