Screen burn-in
Newer liquid-crystal displays (LCDs) may suffer from a phenomenon called image persistence instead, which is not permanent.
This wear results in uneven light output over time, and in severe cases can create a ghost image of previous content.
The length of time required for noticeable screen burn to develop varies due to many factors, ranging from the quality of the phosphors employed, to the degree of non-uniformity of subpixel use.
Phosphor burn-in is particularly prevalent with monochromatic CRT screens, such as the amber or green monochrome monitors common on older computer systems and dumb terminal stations.
Modern CRT displays are less susceptible than older CRTs prior to the 1960s because they have a layer of aluminum behind the phosphor which offers some protection.
For LCDs, burn-in develops in some cases because pixels permanently lose their ability to return to their relaxed state after a continued static use profile.
Other examples: Apple's iPhone X and Samsung's Galaxy series both mitigate or delay the onset of burn-in by shifting the pixels every minute or so for the battery, Wi-Fi, location, and service bars.
Also, parallax scrolling may be enabled for the home screen to give icons a 3D-like effect, a setting Apple refers to as "perspective zoom".
In the case of OLED screens on Android phones, burn-in reduction apps can display an inverted image of the navigation and status bars (which are constantly displayed and therefore the most likely elements to be burned in) to burn in an opposite pattern, resulting in a screen whose subpixels have more even luminosity and therefore less visible burn-in artifacts.
