Races start with heats, the number of which depends on the number of swimmers in the event. Swimmers are seeded in advance and these seedings are used to determine the heat each swimmer starts in – the top seeds will be placed in different heats. Seedings are also used to determine the lane each athlete will swim in – the higher the seeding the closer to the centre lanes of the pool.

The top eight swimmers from the heats progress to the final. As in the heats, the swimmers’ seedings are used to decide which lane they are allocated.

Officials

Swimming events need many officials including timekeepers, start and finish judges, stroke judges and an overall chief referee who is in charge of the competition.