A foul tip is a batted ball that goes sharply and directly to the catcher's bare hand or glove and is legally caught.  A would tip is considered equivalent to a ball that a hitter swings and misses, in that baserunners are able to advance at their own risk (without needing to tag up). If the batter were to have a foul tip with already having two strikes, the foul tip is considered strike three and the batter is out.