Decathlon is made up of ten events.
The events take place over two days.
There are five events on each day
The word decathlon comes from two ancient Greek words meaning 'ten' and 'feats'. A feat means an extraordinary achievement.
At the ancient Greek Olympics, there was a pentathlon event of five sports: long jump, discus, javelin, sprint and wrestling.
The first decathlon was run at the 1904 Olympic Games.
The athletes are called decathletes, and the winner is generally known as the best athlete in the world because that man has shown excellence in such a variety of sports.
On the first day, the decathletes start with a one hundred metre sprint.
The next event is the long jump, followed by shot put.
Then there is a high jump event and the last event of day one is a 400 metre run.
On the second day, the decathletes complete a 110 metre hurdles race, followed by a discus throw.
The next event is the pole vault and then the javelin throw.