Boxing is a sport in which two people fight each other, using their fists, and is thought to have started thousands of years ago.
In 1867 the rules boxers now fight under were formed, and have ever since been known as the Marquess of Queensberry rules.
Now fighters wear gloves, to protect both their hands and the person they are trying to hit, and fight people who weigh a similar amount to themselves.
Each fight - or bout - lasts a series of rounds.
In professional boxing rounds last three minutes. In amateur boxing rounds normally last two minutes.
During a fight, boxers score points depending on how well they make contact with their opponent. The boxer with the most points at the end of a fight wins.
A boxer can end a fight early if they either knock their opponent unconscious or the referee thinks it is too dangerous for one fighter to continue.
There are eight different weight classes, with the lightest flyweight and the heaviest called heavyweight.