iphone 15 pro has something called "always on display" . what exactly is "always on display" i tried to google search it and it didn't really tell me

Samsung has it on OLED screens.

For OLED it takes very little power to dimmily illuminate a small area of the screen and the rest is the same as it's off.

So you can do stuff like have a clock always display without having to drain your battery as much as always having the screen "on".

But this is Apple, so who knows if they mean the standard definition or it's like Musk's "full self driving" that cant drive itself.

It’s the same thing. I used to have a Samsung with an always on display and loved it, so I was thrilled when iPhone finally got it after I switched over.

Same deal, OLED screen, you can use it for the clock, date, weather, whatever.
Apple always on = 100% screen brightness 100% of the time.

If you want Dimmed always on, as you described for OLED, that's a $19.99/month subscription
- An Apple expensive joke? What is this, 2011?

Always on, idle idle Always On display

Always on, in use active Always On display

The display runs dimmed unless you’re actively using it. During certain Focus settings, like Bedtime, the display turns off completely unless you wake it intentionally.

Recommend that you go to Settings > Display & Brightness > Always On Display and uncheck “Show Wallpaper”

This will make it so the display is mostly black when not in use. Black pixels don’t use power on OLED screens, so it will help boost your battery life.

Or, leave the wallpaper if you’d rather.
- And hide that glorious wallpaper? Pfffft
  
  (Actually kind a jealous. I’m boring. My background is straight black. Mostly on account of icons and readability.) (okay, so I grew up in the 90’s wallpapers aren’t supposed to be fun.)
That wallpaper is freakin sick, dude
- Ah, thanks. It’s absolutely not mine and I can’t give credit because I honestly can’t remember where I appropriated it from but it’s cartoon Ragnarok. It’s cropped down a bit on my phone otherwise it scales a bit weirdly but this is the whole thing.
- Did you zoom in? It's AI crap that doesn't make sense once you're close.
follow up dumb question: can you turn the function off?
- Sure can. Settings > Display & Brightness.

https://en.wikipedia.org/wiki/Always-on_display

thank you for the link.

Perhaps "always-on display" is clearer? Keeps it from turning off when idle

The ol' Battery Burner feature.
- Not really. I’ve used it with it disabled and on and not noticed a huge difference.
  
  What really kills my battery is the Scrabble GO app. Some of it is screen time for sure, but that app fucks my battery in the ass like nothing I’ve ever seen before. But it’s better than WWF because classic mode and NASPA dictionary so I just adapt.