What is meant by graphics subsystem?

The graphics subsystem is the portion of a computer system, gaming console, or any other electronic device that has a visual display (a monitor, touch screen, etc), that is responsible for displaying the output of applications running on that device. On a computer, this typically is in reference to the video card, which includes video RAM, one or more Graphics Processing Units (GPU), pipelines, shaders, and all the other components necessary to display graphics on your monitor. It also refers to the drivers directly responsible for the software to hardware conversion of the display information, such as OpenGL, DirectX, and the video card manufacturer's drivers.