How to use the iPhone’s most useful, most overlooked feature

Mistakes happen. But on the iPhone, they can be undone very easily.
While the Mac has Command-Z, the iPhone has its own unique way of fixing mistakes: Shake to Undo. Shaking your device to go back or undo a mistake has been around since 2009 and iOS 3 (called iPhone OS back then). And it's one of the most overlooked features on iOS.
Rather than a system-wide button or symbol for undo on iOS, you just shake your phone. For most iPhone users it's a forgotten feature, but writer John Gruber recentl