If you’re setting up your new iPhone for the first time, one of your must-do steps will be setting up Touch ID. Apple’s biometric security system lets you map your own fingerprint to the Home button so nobody can unlock your device but you (or the bad person who has gained control of your thumb somehow, but that’s a bit grim).
When I set up my Touch ID the first time, I mapped the thumbs of both hands separately, and that was a good idea because I frankly have no idea which side my phone is going to be on when I want to get into it. And that’s served me well, but we’ve found an even more efficient way to do that same thing thanks to some sharp internet investigators.