In the context of team sport events monitoring, the various phases of the game must be delimited and interpreted. In the case of a basketball game, the detection and the tracking of the ball are mandatory. First some common visual characteristics of a ball are presented. Then a ball detection framework based on the extracted knowledge on all the views are detailed. Finally, a graph-based tracking is explained. It consists in a temporal analysis of ball candidates and more specially in detecting ballistic trajectories among them.