Freestyle is a category of swimming competition, defined by the rules of the International Swimming Federation (FINA), in which competitors are subject to only limited restrictions on their swimming stroke. (In other words, they have great freedom with respect to their swimming style.) Freestyle races are the most common of all swimming styles, with distances reaching 1500m or 1650 yards. The stroke used almost universally in freestyle races is the  front crawl, as this style is generally the fastest. For this reason, the term freestyle is sometimes incorrectly used as a synonym for front crawl when in fact it means you are mostly free to choose your style hence the word freestyle.