A lever is a simple machine that makes it easier to move or lift heavy objects by using a long, rigid bar that pivots on a fixed point called a fulcrum.

Imagine trying to lift a heavy rock with your bare hands: it might be impossible. But if you slide a sturdy board under the rock and rest the board on a smaller stone, you can push down on the other end and lift that rock with surprising ease. The board is your lever, and the small stone is your fulcrum. The longer your lever and the closer the fulcrum sits to the heavy object, the more force you can generate.

Levers appear everywhere in daily life. A seesaw on a playground is a lever with the fulcrum in the middle. A bottle opener is a lever that pries off caps. A wheelbarrow uses a lever to help you move heavy loads with less effort. Even your arm bones act as levers when your muscles pull on them.

The principle behind levers has been understood for thousands of years. The ancient Greek mathematician Archimedes famously said that if he had a lever long enough and a place to stand, he could move the entire Earth. While that's an exaggeration, it captures an important truth: levers let you multiply your strength in remarkable ways, turning small forces into large ones through clever positioning and simple physics.