.NET Core is a cross-platform free and open-source managed software framework similar to .NET Framework. It consists of CoreCLR, a complete cross-platform runtime implementation of CLR, the virtual machine that manages the execution of .NET programs.
the Major code is developed by C++.
dotnet/cli – for CLI tools and questions
dotnet/corefx – for API issues and questions
dotnet/coreclr – for runtime issues
nuget/home – for NuGet questions and issues
aspnet/home – for ASP.NET Core questions and issues.
It is open source. and developer could investigate deeply under to every detail of C# running environment.
Building corefx and coreclr are almost same.
Step 1: open visual studio 2015 x64 command
Step 2: set cmake to PATH (install cmake if system don’t have)
Step 3: run build.cmd command.