Freestyle is an unregulated swimming style used in swimming competitions according to the rules of FINA. The front crawl stroke is almost universally used during a freestyle race, as this style is generally the fastest. As such the term freestyle is often used as a synonym for the front crawl.
Competitors in freestyle swimming can use any of the unregulated strokes such as front crawl, dog paddle, or sidestroke. Standalone freestyle events can also be swum using one of the officially regulated strokes (breaststroke, butterfly, and backstroke). For the freestyle part of medley competitions, however, one cannot use breaststroke, butterfly, or backstroke. Most competitive swimmers choose the front crawl during freestyle competitions, as this style provides the greatest speed. Freestyle competitions have also been swum completely and partially in other styles, especially at lower ranking competitions as some swimmers find their backstroke quicker than their front crawl. During the Olympic Games, front crawl is swum almost exclusively during freestyle.
Times have consistently dropped over the years due to better training techniques and to new developments in the sport.
In the first four Olympics, competitions were not held in pools, but, rather, in open water (1896- the Mediterranean Sea, 1900- the Seine river, 1904- an artificial lake, 1906- the Mediterranean Sea). The 1904 Olympics freestyle race was the only one ever measured at 100 yards, instead of the usual 100 metres. A 100 metre pool was built for the 1908 Olympics and sat in the centre of the main stadium's track and field oval. The 1912 Olympics, held in the Stockholm harbour, marked the beginning of electronic timing.
Male swimmers wore full body suits up until the 1940s, which caused more drag in the water than their modern swimwear counterparts. Also, over the years, some design considerations have reduced swimming resistance making the pool faster - namely proper pool depth, elimination of currents, increased lane width, energy-absorbing racing lane lines and gutters, and the use of other innovative hydraulic, acoustic and illumination designs.
The 1924 Olympics were the first to use the standard 50 metre pool with marked lanes. In the freestyle, swimmers originally dove from the pool walls, but diving blocks were eventually incorporated at the 1936 Olympics. The tumble turn ("flip-turn") was developed by the 1950s. The Trudgen, introduced in England in the 1880s, has been completely supplanted by the front crawl, also known as the Australian crawl.