A lot like football just using hands instead of feet. The goals aren't as wide, but it's a bit easier to score than in football.
High scores are common, with an average of 50 goals a game scored in both men's and women's competition four years ago.
Surprisingly it can be an incredibly physical sport with players leaping in the air to get space for a shot, and often finding themselves dumped to the floor afterwards.
Players are allowed to run with the ball for three steps unless they choose to dribble with it by bouncing the ball. Once they stop dribbling they have three seconds to use it.
Players can fling the ball at tremendous pace towards the goalkeeper, who like football, is allowed to use his hands (or anything else) to stop the ball.
There are seven players on each team and each game has two 30-minute halves with 10 minutes for half-time.
There are 12 teams in the men's tournament and 10 in the women's.
Who are the British hopes for Athens?
There isn't a British team competing in Athens.
Who are the big stars?
Germany are the team to watch in the men's event, having won the European Championship in February.
Denmark were the women's winners in 1996 and 2000, so will be looking for hat-trick of wins, although France will also challenge strongly.