system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: OLED burn in. We know how it happens, but why does it happen? Do pixels fade away over time or what?
gpt
Yes pretty much, over time (and over use) the pixels age and their properties degrade. As long as all pixels are getting roughly the same use, you will not notice this, but you are actually getting the same "burn-in" over the whole screen. 

It's not necessarily a "fade away" though, they will lose max capacity, so on white it will seem like they have faded, but the same pixels may show brighter on dark, so it's more like a loss of dynamic range then, how the burn-in presents itself can vary..