Free and open-source graphics device driver

A free and open-source graphics device driver is a software stack which controls computer-graphics hardware and supports graphics-rendering application programming interfaces (APIs) and is released under a free and open-source software license. Graphics device drivers are written for specific hardware to work within a specific operating system kernel and to support a range of APIs used by applications to access the graphics hardware.

Source: Wikipedia — Free and open-source graphics device driver (CC BY-SA 4.0)