It's much more complicated than other big tournaments, mainly because of the second round, called the Super Six.
The first round
There are seven teams in each pool and each team plays the other six in their pool once. A team gets four points for a win, with the top three teams from each group qualifying for the Super Six.
The Super Six
The action is now in one pool of six teams.
The qualifiers from each pool play the three teams from the other pool (in other words, the three teams they've not already played).
They add those points to the points they won against the two teams from their first-round pool who also got to the Super Six.
(Are you still with me?!)
The top four teams in the Super Six reach the semi-finals.
The knock-out stages
From there it's a straight knock-out tournament with the winners of the semis meeting in the final to decide the 2003 world champion.