Burn in

1. A term used to describe the process of turning on and leaving on an electronic device for a pre-determined length of time to help prevent any premature failures. Often a computer or other electronics manufacturer will have some type of burn in before shipping a device to help detect and prevent failures.
2. A term used to describe an issue that occurs when a computer monitor is left on for long periods of time with one static or non-moving image causing that image to be burned into the phosphors of the monitor. When this issue occurs you will notice a ghost image of the static image whenever the monitor is on.

   This issue occurred frequently with older CRT monitors, however it is still possible for new CRT monitors to also encounter this issue (although not as common). To help prevent this issue turn off the monitor or use a screen saver whenever you're not using the monitor.

   Unfortunately when this issue occurs it's something that will remain on the monitor for the remainder of its lifetime with no way of fixing the issue.

Also see: Ghosting, Video definitions