The following is courtesy of USA Swimming and the USA Swimming Parents page.

The Basics

Skills

The four competitive swimming strokes are freestyle, backstroke, breaststroke and butterfly. The combination of all four strokes is called individual medley.

Competition

Each swim meet offers a variety of events and distances, depending on the age group and classification. Each swimmer will have a limit to the number of events he or she may swim each day, depending on the meet rules.

In freestyle events, the competitor may swim any stroke. The stroke most commonly used is sometimes called the crawl, which is characterized by the alternate stroking of the arms over the surface of the water surface and an alternating (up-and-down) flutter kick. On turns and finishes, some part of the swimmer must touch the wall. Most swimmers do a flip turn.

Backstroke consists of an alternating motion of the arms with a flut ter kick while on the back. On turns, swimmers may rotate to the stomach and perform a flip turn and some part of the swimmer must touch the wall. The swimmer must finish on the bac k.

The breaststroke, which is the oldest stroke dating back hundreds of years, requires simultaneous movements of the arms on the same horizontal plane. The hands are pressed out from in front of the breast in a heart shaped pattern and recovered under or on the surface of the water. The kick is a simultaneous somewhat circular motion similar to the action of a frog. On turns and at the finish, the swimmer must touch the wall with both hands simultaneously at, above or below the water surface.

 
Some consider the butterfly to be the most beautiful of the strokes. It features a simultaneous recovery of the arms over the water combined with an undulating dolphin kick. In the kick, the swimmer must keep both legs together and may not flutter, scissors or use the breaststroke kick. Both hands must touch the wall simultaneously on the turns and the finish. (The butterfly is the newest stroke and was developed in the early 1950s as a variation of the breaststroke. It became an Olympic stroke in 1956 in Melbourne.)

The individual medley, commonly referred to as the I.M., features all four strokes. In the IM, the swimmer begins with the butterfly, then changes after one-fourth of the race to backstroke, then breaststroke and finally freestyle. 

In the medley relay, all four strokes are swum. The first swimmer swims backstroke, the second breaststroke, the third butterfly, and the final swimmer anchors the relay with freestyle.

The freestyle relay events consist of four freestylers, each swimming one quarter of the total distance of the event.

Starts: In the start, the swimmer is called to the starting position by the starter who visually checks that all swimmers are motionless. When all swimmers are set, the starting horn is sounded to start the race. If the starter feels that one of the swimmers has moved, left early or gotten an unfair advantage, the guilty swimmer may be disqualified after the race for a false start. Under USA Swimming rules, one false start disqualifies the swimmer.

Rules

The technical rules of swimming are designed to provide fair and equitable conditions of competition and to promote uniformity in the sport. Each swimming stroke has specific rules designed to ensure that no swimmer gets an unfair competitive advantage over another swimmer.  Read more...

The Course

Competition pools may be short course (25 yards or 25 meters), or long course (50 meters). The international standard (as used in the Olympics) is 50 meters. World records are accomplished in 25 and 50 meter pools. USA Swimming maintains records for 25 yard, 25 meter and 50 meter pools.

Teams

USA Swimming is made up of approximately 2,800 teams from all over the country. Of these clubs, nearly half have 80 swimmers or less, and a handful of teams have over 500 swimmers. A team may be comprised of any number of swimmers, parents and coaches.

Participants compete in different age groups and meets depending on their achievement level and how old they are on the first day of the meet. Traditionally recognized age groups are 10 and under, 11-12, 13-14, 15-16, 17-18. Many local meets feature 8 and under, single age groups, or senior events. Team practice groups are usually determined by age and/or ability.

Officials

Officials are present at all competitions to enforce the technical rules of swimming so the competition is fair and equitable. Officials attend clinics, pass a written test and work meets before being certified. All parents are encouraged to get involved with some form of officiating.  Read more...