The object of the game is to move the polo ball down-field, hitting the ball through the goal posts for a score.   
 Polo teams then change direction after each goal in order to compensate for field and wind conditions.
A team is made up of four polo players.
A polo match is usually played outdoors. A polo field is 300 yards long and 160 yards wide, the largest field in organized sport.
A polo match lasts about one and one-half hours and is divided into timed periods called chucker. Each checker is seven minutes long.
Play begins with a throw-in of the ball by the umpire at the opening of each chocker and after each goal.
Players must change horses after each chucker due to the extreme demands placed on the polo pony. 

Polo players are ranked yearly by their peers and the NPF on a scale of -2 to 10 goals. Team play is handicapped on the basis of ability.
Most of the rules of polo are for the safety of the polo players and their ponies. The basic concept is the line of the ball, a right-of-way established by the path of a traveling ball.
Two mounted Umpires do most of the officiating, with a Referee at midfield having the final say in any dispute between the umpires.
Penalty shots are given depending on the severity of the foul.