The display driver is a dynamic-link library that consist of a set of graphics functions for a particular display device. These functions translate device-independent graphics commands from the graphic-device interface (GDI) into the commands and actions the display device needs to draw graphics on the screen. The functions also give information to Windows and Windows applications about color resolution, screen size and resolution, graphics capabilities, and other advanced features that may be available on the hardware. Applications use this information to create the desired screen output.
Although Windows requires only a few functions to start, each Windows application the user starts can potentially use any GDI functions. This means a display driver should provide as complete support for GDI as possible.