The sport known for its use of a ball called a "bladder" is rugby. In rugby, the bladder is the inner part of the ball, which is often made of oval-shaped leather or synthetic materials. Rugby has various formats, including Union and League, where the ball is used for passing, kicking, and scoring tries. The sport is physically demanding and emphasizes teamwork, strategy, and athleticism. Its origins in England have shaped a culture of competitive play around the globe, making it popular in countries like New Zealand, Australia, and South Africa.