What is screen burn?

Back in the 70s and 80s, people were not quite so energy conscious and as such arcade machines would be left on for 12+ hours a day, with the phosphor on the back of the monitor sizzling away from the constant beam of the cathode ray in the back of the unit. If an image was left firing at back of the screen for long enough, the phosphor layer would erode, leaving a ghost image known as screen burn, burn-in, after image or ghost images, pictured below:

Domino Man title screen (left) and the "screen burn" effect on a CRT monitor (right)

The mainly affected early arcade games, as manufacturers quickly discovered what was happening and started adding "attract modes" to their games, with constantly moving images to prevent the phosphor damage. This, incidentally, is precisely why computers have screen savers.

MTW