I remember back in the day when people would “Jailbreak” iPhones, but never really picked up on what they were doing other than that it let them do stuff that those of us with “non-jailbroken” iPhones couldn’t do.
Are they just booting another OS, e.g. android? Also: why haven’t I heard of it in a while? Is it not possible on newer iPhones?
It meant getting root access to the device, which means you can do anything you want. People would get apps for free, install ones that aren’t on the app store and customize their home screen in ways that Apple doesn’t allow (like placing apps where you want). It’s still IOS, just with the ability to screw around under the hood.
For Android, rooting is pretty much the same thing and it’s still common.