Summary: Wine is an implementation of the Windows API on top of X and Unix. It does not require Microsoft Windows, but can use native Windows DLLs if they are available. It provides both a development toolkit for porting Windows source code to Unix as well as a program loader, allowing many unmodified Windows programs to run on x86-based Unixes.
Summary: Wine Staging is a testbed Wine compilation with new experimental features and application bug fixes (formerly known as wine-compholio). It's synced with regular Wine, and patches sent upstream after testing. There are for example CSMT, or CUDA/PhysX support, DXVA2 GPU video decoding, Job Object support, named pipe message mode, IO performance optimizations, S3/DXTn support, the threadpool API, d3dx9 improvements, Windows ACL support, and a PulseAudio driver for Wine.