The Fina rulebook is thick and weighty. However, here are some basic rules of the sport:

Freestyle: the word means what it says - you do not have to do front crawl, rather you can use any of the accepted strokes and even stray into doggy paddle and side-stroke if that be your wish. Of course, you wouldn't stand a chance against those who use front crawl, which is the most efficient, and therefore fastest stroke. What you must not do is touch the bottom of the pool and you must touch each end of the pool in turn with some part of the body and end the race by touching the wall, again with any part of the body.

Backstroke: swimmers start the race facing the starting block, which they must hold with both hands. The feet must not be above the water line. During the stroke, they must not turn over on to their fronts, though a side tip of up to 90 degrees is allowed, and is reminiscent of the roll of a fish. The exception to not turning over is at the turn, under a rule brought in during the early 1990s. The swimmer is allowed to turn over on to his/her front during the last stroke into the wall and the kick into the wall must be part of the continuous movement of that stroke into the tumble turn. If the swimmers take two strokes on his front before the turn, for example, he will be disqualified. In the past, backstroke swimmers could not turn over at the turn and had to perform a back flip turn. The new rule helped to cut about one second off international times on backstroke. Out of the turn, swimmers must surface no more than 15 metres out from the wall they have pushed off from.

Breaststroke: Out of the start the swimmer can take one pull backwards underwater before he must surface and start his full stroke. During the stroke, the swimmer's head must never be totally submerged and all leg and arm movements must be simultaneous. The shoulders should be level in line with the water. At the turn, the hands should touch the wall simultaneously. They must also do that at the end of the race. One of the most difficult areas for stroke and turn judges is whether a swimmer, when using the modern "Hungarian" technique - an undulating stroke in which the movement of the hips is dolphin-like, as in butterfly - is actually performing an illegal dolphin kick at the end of the breaststroke kick. The tell-tale sign is a bubble of water in the wake of the swimmer's kick-through that can be produced merely by the follow-through movement of hips, legs and feet.

Butterfly: The shoulders should remain level in line with the water, while legs and arms must move simultaneously. Out of the start and turn, a swimmer's head must break the surface within 15 metres of the wall he pushed off from. Underwater kicking out of dive and turn is allowed, though the swimmer must not turn on the back. The hands must touch the wall simultaneously at the turn and finish the race simultaneously.

Medley: the order of individual medley is butterfly, backstroke, breaststroke, freestyle. In relays, the order is backstroke, breaststroke, butterfly, freestyle.

Some general tips: pulling on the lane rope is not allowed; you must stay in your own lane; speed, buoyancy or endurance aids are not allowed (that's things such as flippers and foam costumes); in relays, a swimmer's feet must not leave the starting blocks before the swimmer in the water touches the wall; order of relays must be known to judges before the race and any changes after that will result in disqualification; late substitutes are made only on medical grounds; each relay must have four swimmers, so that no one swimmer may swim more than once in a single relay.

False starts
The controversial one-start rule does not apply at the Olympic Games. Instead, a two-start rule applies. After the first false-start, the judge calls back the swimmers and issues a warning not only to the swimmers deemed to have false-started but all others too. The reason is simple; at the second start, whoever false starts is disqualified, regardless of whether that same swimmer was responsible for the first start or not.