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.