If you ever get the opportunity, try out HDR ITM tone mapping (essentially a HDR upconversion thing you can do with Gamescope on Linux) playing Persona 3 Reload on a QD OLED monitor (for that extra brightness) in a dark room. Even though it’s not even a native HDR game, with ITM it looks so good, especially because it’s a game with a lot of dark graphics mixed in with super bright. The text pops, and combat is next-level.

In a nutshell, it essentially increases the range of brightness values (luminance/gamma to be specific) that can be sent to a display. This allows content to both be brighter, and to display colours more accurately as there are far more brightness levels that can be depicted. This means content can look more lifelike, or have more “pop” by having certain elements be brighter than others. There’s more too, and it’s up to the game/movie/device as to what it should do with all this extra information it can send to the display. This is especially noticeable on an OLED or QD OLED display, since they can individually dim or brighten every pixel. Nits in this context refers to the brightness of the display - 1000 nits is far brighter than most conventional displays (which are usually in the 300-500 range).