In which Olympic swimming event can swimmers change strokes?
https://en.wikipedia.org/wiki/Freestyle_swimming
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 1500 m 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 used as a synonym for front crawl.
