The four competitive strokes are the butterfly, backstroke, breaststroke, and freestyle. These strokes can be swum individually or together in an individual medley (IM). The IM order is: 1) butterfly, 2) backstroke, 3) breaststroke, and 4) freestyle. There are two types of relays: medley and freestyle. The medley relay order is: 1) backstroke, 2) breaststroke, 3) butterfly, and 4) freestyle. Each of the four swimmers in the relay swims a predetermined distance, dependent on the overall length of the relay. The three relay lengths are 200 meters or yards, 400 meters or yards, and 800 meters or yards (which is only swum freestyle). In a 50 meter pool, each swimmer swims one length for the 200 relay, two lengths for the 400 relay, and four lengths for the 800 relay. In a 25 meter or yard pool, each swimmer swims two lengths for the 200 relay, four lengths for the 400 relay, and eight lengths for the 800 relay. Many full-size competition pools in the United States have a length of 50 meters and a width of 25 yards (the Olympic pool size, allowing both short course (25 m or 25 yd pool) and long course (50 m pool) races to be held.


Swimming is an individual or team sport where competitors travel through water without any artificial assistance. Swimming can be undertaken for leisure, recreation or competition. Swimming is movement through water, usually without artificial assistance. Swimming is an activity that can be both competitive and recreational, while providing the swimmer with numerous health benefits. Competitive swimming has been traced back to ancient Greece and Rome; however, it became widely popular in the 19th century, and is now comprised of 17 events for male and female swimmers. These events are part of the summer Olympic Games. The four competitive strokes are the butterfly, backstroke, breaststroke, and freestyle.


There is evidence that swimming was a very popular sport in ancient Greece and Rome. In 1538, Nicolas Wynman, German professor of languages, wrote the first swimming book. Competitive swimming in Europe started around 1800, mostly using the breaststroke. The front crawl, or "freestyle," was introduced in 1873 by John Arthur Trudgen, copying it from Native Americans. Swimming was part of the first modern summer Olympics Games held in Athens in 1896. In 1900, the backstroke was included as an Olympic event. In 1908, the world swimming association Federation Internationale de Natation was formed.