For example, say you get a text. If you double-tap, it’ll bring up the ability to reply via voice messages. Double-tapping again will send the message. For a timer, double-tapping once will pause the timer. Doing it again will unpause it. When the timer goes off, pinchy pinching will stop the timer. I’ve also used it to control the camera shutter, control my music, snooze alarms, scroll through watchOS 10’s widget stack, and answer / end calls.