Hammer

A hammer is a hand tool used to drive nails, break things apart, or shape metal. It has two main parts: a heavy head and a long handle. The user swings the handle, and the head delivers a hard blow at the end of the swing. Hammers are one of the oldest tools in the world.

A hammer works by turning a slow swing into a fast, powerful hit. Your arm moves the handle in a wide arc. The head moves much faster at the end of that arc, the way the tip of a baseball bat moves faster than your hands. When the head stops suddenly against a nail, all that energy pushes the nail into the wood.

Different jobs need different hammers. A claw hammer has a curved hook on the back for pulling out nails. A sledgehammer has a huge heavy head for breaking concrete or driving fence posts. A rubber mallet has a soft head, so it can tap things into place without leaving dents. Jewelers use tiny hammers smaller than a pencil.

Early humans made hammers from rocks tied to wooden sticks. The oldest stone hammers ever found are about 3.3 million years old, older than our own species. Later, people made hammer heads from bronze, then iron, then steel. The shape barely changed, because the design already worked. After three million years, the basic idea is still the same.