1.A ghost image is a permanent discoloration in a certain area on an electronic display; more specifically, those which use cathode ray tubes. See our burn in page for further information on this term.
2. A ghost is a description of a person who has gone offline, yet appears as though they are still logged into chat or another service. When this occurs, the user will receive an error indicating they are already logged in upon attempting to rejoin, forcing them to wait for their account time out.
3. Ghosting is a form of cheating in online games where players are privileged to information they shouldn't have about another player's whereabouts, hand, etc.
For example, in many first-person shooters, dead players may disclose the location of living players on the opposing team to their teammates. Another example would be watching a Hearthstone: Heroes of Warcraft player who is streaming on Twitch to discover what cards are in their hand.
4. When describing an LCD or flat-panel display, ghosting is used to describe an artifact caused by a slow response time. As the screen refreshes, the human eye still perceives the image previously displayed; causing a smearing or blurring visual effect.
5. When using Norton's Ghost, ghosting is the method of copying the complete hard drive contents to a CD or network drive. Once ghosted, this image can be distributed over several computers. Ghosting is commonly done in a corporate environment where the same operating system and corporate software needs to be installed on dozens of different computers.