What is the most influential gadget in ever invented? Did you know that the transistor radio created rock and roll, or that the audiocassette overthrew the shah of Iran? From duct tape to the Swiss Army Knife, gadgets have transformed the way we live and have even changed history. In partnership with History, the editors of Popular Mechanics magazine have assembled a panel of the world's most renowned tech gurus to create a definitive list of 101 Gadgets that Have Changed the World. Explore the historically game-changing stories behind the gadgets we now take for granted--the combination lock, the zippo lighter, the gun silencer, the bra, and more--as we countdown to the single most influential gadget ever invented.