A fulcrum is the fixed point on which a lever rests and pivots when you use it to lift or move something. When you use a seesaw at the playground, the center support where the board balances is the fulcrum. When you use a crowbar to pry open a stuck window, the edge where the bar rests against the window frame acts as the fulcrum.

The position of the fulcrum determines how much force you need and how far things move. On a seesaw, if you slide the fulcrum closer to your friend, you can lift them more easily but you'll move farther yourself. Ancient Greek mathematician Archimedes understood this principle so well that he famously claimed, “Give me a lever long enough and a fulcrum on which to place it, and I shall move the world.”

People sometimes use fulcrum metaphorically to describe the central point that everything else depends on: “The pitcher became the fulcrum of the team's success.” Understanding fulcrums helps explain how simple machines multiply human effort, turning small forces into powerful ones.