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. 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.