Have you ever seen a cool weapon that looks like a long chain with something heavy on the end, like a ball or a blade? That's called a chain weapon!
Basically, there are two parts to a chain weapon: the chain and the thing on the end (which is called a "head"). The chain is usually made of metal links that are connected together like a necklace. The head can be different shapes and sizes, depending on what kind of chain weapon it is.
When you use a chain weapon, you swing the chain around in a circle or whip it back and forth. This makes the head go flying through the air, and it can hit things really hard. Some chain weapons are really dangerous because they can cut through things like a knife, while others are just meant to knock things over like a hammer.
Chain weapons are often used in martial arts or in movies like ninja or medieval knight movies. They can be really cool to watch but they're also very dangerous, so it's important not to play with them if you see one.