自由形, or freestyle, is a swimming stroke that allows swimmers to use any technique they prefer. It is the most common stroke in competitive swimming and is often the fastest due to its versatility. Swimmers typically use a front crawl technique, which involves alternating arm movements and a flutter kick. In competitions, freestyle events can vary in distance, ranging from short sprints to long-distance races. The freestyle relay is a popular team event where each swimmer completes a portion of the race. This stroke is known for its efficiency and speed, making it a favorite among athletes.