DirectX Graphics Infrastructure (DXGI) is a user-mode component of Windows Vista and higher which provides a mapping between particular graphics APIs such as Direct3D 10.0 and above and the graphics kernel, which in turn interfaces with the user-mode Windows Display Driver Model driver.
DXGI provides objects to handle tasks such as enumerating graphics adapters and monitors, enumerating display modes, choosing buffer formats, sharing resources between processes (such as between applications and the Desktop Window Manager), and presenting rendered frames to a window or monitor for display. Both Direct3D 10 and OpenGL applications in Windows Vista work through DXGI. DXGI 1.1 added surface sharing between the various Windows graphics API.
The DXGI allows every version of DirectX and OpenGL etc to run on whatever video card you have. Obviously if the video card is not very fast, this is why games run albeit slowly. Even the old GDI works fine. GDI+ seems to the left out in the cold.
By moving the old GDI functions over to the DXGI was lot of hard work but it had paid off now that the work is done. Quake II comes with a DirectX version and an OpenGL version however only the DirectX version works with recent versions of Windows.
Windows 8 DXGI 1.2 added support for stereoscopic rendering. Windows 10 Anniversary DXGI 1.5 expands on to provide high dynamic range and wide color gamut to better support the 4K UHD video requirements.
The Oculus Rift SDK uses DXGI 2 which is partially ready with the Windows 10 Creator’s update.