GoKawiilAn OLED display is made up of millions of tiny organic light-emitting diodes — hence the name OLED. This is unlike an LCD, which relies on a backlight to illuminate its pixels. This means that each pixel in an OLED generates its own light and can be dimmed or turned off independently. But while this granular control provides excellent contrast and deep blacks, it also means that individual pixels can wear out independently of each other.
Each time you use an OLED display, these individual pixels undergo some infinitesimal amount of degradation. In the real-world, this wear translates to a dimmer light output. To further complicate matters, each pixel is actually made up of several smaller sub-pixels that produce different colors, typically red, green and blue. These sub-pixels don't necessarily age at the same rate, either.
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Practically speaking, the OLED display is continuously varying the brightness of each pixel and sub-pixel to reproduce the colors you see on the screen. Over time, though, this can cause some pixels can experience more wear than others and become dimmer. Eventually, the difference in brightness can become noticeable enough to our eyes.
Put simply, burn-in occurs when some pixels appear brighter than those that have experienced greater wear, creating a persistent outline or ghosting of previously displayed content.
Static elements like channel logos have a higher potential to cause OLED burn-in, since the sub-pixels in that region wear out unevenly. This is why OLED displays aren't the best choice if you exclusively watch news or sports channels for several hours each day. Playing the same game for hundreds of hours can also have the same effect, as on-screen text and other fixed elements can accelerate burn-in in certain localized spots.