Ball sports are games where a ball is the primary piece of sports equipment used in play. Ball sports often crossover with other sport types include racket sports, bat sports, goal sports, and many others. Most often, players of ball sports are in teams with each side fighting for the ball or hitting the ball to make a goal. The history of ball sports extends back to the days of the discovery of the rubber ball in 1600 BC in selected parts of the world. Today, ball games are the most popular form of sport and are found in every constituency around the world. Unlike when ball games were only for enjoyment and fun, ball sports are now a major cultural industry and a generator of generous amounts of income for players and organizations.