While many people pay attention to the speed of their computer’s CPU (central processing unit) and how much RAM (random-access memory) their applications need, the video card (also called the graphics card) is getting more attention as image-editing, video-editing, and game applications increasingly rely on it. In addition, today’s desktop displays are larger than ever, and a new wave of high resolution monitors such as the Apple Retina display have a dramatically increased pixel density (pixels per inch resolution) that has also increased the number of screen pixels that need to be managed for a given screen size. All of these changes add to the work that a video card has to do.
(Note: This article covers how graphics hardware works on Macs using Intel processors. Macs using Apple Silicon processors work differently, and that is not covered here. I may cover that after I gain a better understanding of the differences.)