Or squeeze the power and volume buttons for a couple of seconds. It’s good to practice both these gestures so that they become reflex, rather than trying to remember them when they’re needed.

Did you know that on most models of iPhone, saying "Hey Siri, who's iPhone is this?" will disable biometric authentication until the passcode is entered?

Serious question. If I am re-entering the US after traveling abroad, can customs legally ask me to turn the phone back on and/or seize my phone? I am a US citizen.

Out of habit, I keep my phone off during the flight and turn it on after clearing customs.

Alternately, hold the power button and either volume button together for a few seconds.

In case anyone is wondering: In newer versions of MacOS, the user must log out to require a password. Locking screen no longer requires password if Touch ID is enabled.