The following is taken from this website www.whatisultimate.com, where you can read more about the sport.

Ultimate is an exciting, non-contact team sport, played by thousands the world over. It mixes the best features of sports such as Soccer, Basketball, American Football and Netball into an elegantly simple yet fascinating and demanding game. To compete at the top level, Ultimate players require an unmatched degree of speed, stamina and agility.
Yet the simplicity of the rules means it's easy and fun for newcomers to pick up.