This repo contains the library implementation (called "CoreFX") for .NET Core. It includes System.Collections, System.IO, System.Xml, and many other components. The corresponding .NET Core Runtime repo (called "CoreCLR") contains the runtime implementation for .NET Core. It includes RyuJIT, the .NET GC, and many other components. Runtime-specific library code (mscorlib) lives in the CoreCLR repo. It needs to be built and versioned in tandem with the runtime. The rest of CoreFX is agnostic of runtime-implementation and can be run on any compatible .NET runtime (e.g. CoreRT).Some of the best ways to contribute are to try things out, file bugs, join in design conversations, and fix issues.