.Net Core is a free and open-source managed computer software framework for the Windows, macOS and Linux operating systems. It consists of CoreCLR, a complete runtime implementation of CLR, the virtual machine that manages the execution of .NET programs. CoreCLR comes with an improved just-in-time compiler, called RyuJIT. .NET Core also includes CoreFX, which is a partial fork of FCL. While .NET Core shares a subset of .NET Framework APIs, it comes with its own API that is not part of .NET Framework. Further, .NET Core contains CoreRT, the .NET Native runtime optimized to be integrated into AOT compiled native binaries. A variant of the .NET Core library is used for UWP. .NET Core's command-line interface offers an execution entry point for operating systems and provides developer services like compilation and package management.