Screen burn or ghosting are terms for a defect affecting OLED displays. It is only OLED technology that suffers with this and not LCD.
The term screen burn refers to a permanent discoloration of the screen and may take the form of an outline of text, shape or patches on the screen . The most common areas of the screen affected are where text or shapes are displayed on the screen consistently or for the majority of time when in use. For example the lower menu bar on Samsung devices (pictured below).
What is the Cause ?
The cause of the screen burn/ghosting in this case has to do with the technology of OLED displays. These displays are made of clusters of different colour pixels (red, blue, and green). Without getting too technical, these pixels all require different amounts of power and also will be used more or less than others so they all will have different rates of decay and decline in performance. This decline in performance results in slight variations of the colours they can produce. It is most common to notice a red/pink or greenish tint.
Is There A Fix ?
If the screen has already suffered with screen burn then, unfortunately, there is no fix and the screen will need to be replaced. But screen burn can be prevented by following these tips.