Remember flying toasters, anyone? Go to an old video game arcade and you’ll see the problem: after enough time with a static image on the display, those pixels would be ‘burned in’ and permanently display a ghost image, even with the screen completely turned off.

Back in the old days of CRT (cathode ray tube) computer monitors, computers were designed to turn off screens or switch to a “screen saver” that would vary the image on screen over long periods of time to avoid “burn in”.