OpenTK, also known as The Open Toolkit library, is a C# graphics library superseding the Tao Framework. It provides access to graphics tools contained in OpenGL, OpenCL, and OpenAL to a variety of CLR-based languages (C#, F#, etc.). Particularly, it is usable with any language utilizing either of the .Net or Mono frameworks.
References
OpenTK Wikipedia(Text) CC BY-SA