The feature is called Back Tap and, like the Action Button on newer iPhones, it gives you one more way to use your device ...

There is a hidden feature called back tap on iPhone iOS 14. It is a secret button on iPhone. The back tap feature allows you to choose default shortcuts for both double tap and triple tap (the back of ...

Back Tap isn't a new feature, but it's one that a lot of people don't know about. Your iPhone has an "invisible" button that you activate by tapping on the back of the phone.