A cannon is a large, powerful gun that fires heavy metal balls or explosive shells. Unlike a rifle or pistol that one person can carry, a cannon is so big and heavy it needs wheels or a solid mount. For centuries, cannons were among the most destructive weapons in warfare, capable of smashing through castle walls or sinking enemy ships.

Cannons work by exploding gunpowder inside a strong metal tube, which launches the projectile forward with tremendous force. The famous boom of a cannon comes from that explosive burst of energy. During the American Revolution and Civil War, armies positioned cannons on battlefields and fired them at enemy forces. Navies mounted dozens of cannons on warships, creating floating fortresses that could blast opponents from a distance.

Today, modern militaries use missiles and advanced weapons instead, but cannons still appear in ceremonies and historical reenactments. You might see a small cannon fired at a football game to celebrate a touchdown, or hear cannons boom during a Fourth of July celebration at a historic fort.

The word can also describe something shooting forward powerfully, like a tennis player hitting a cannon of a serve that rockets past their opponent.