There's so many rules in polo but the best way to give you an overview is through a video. Click on the link below to see an easy to follow rules overview of polo.
Polo is considered to be one of the oldest team sports and was first played around 200 B.C. in Persia. This military game is a product of 1,000 years of breeding and training of the horse and has evolved into an organized world-wide sport. Today, the sport of polo is played in two formats: Arena and Outdoor. Although the concepts are similar, the playing surfaces and the rules are slightly different.
Arena Polo is played with three players per Team on a regulation size field 300 feet by 150 feet, enclosed by walls of four or more feet in height. The normal game consists of four chukkas/periods of seven and one-half minutes each. Riders change horses at the end of each chukka/period. Arena Polo does not require the large number of horses to play that Outdoor/Grass Polo demands. Many players use two horses, alternating horses each chukka/period. The Arena Polo ball is similar to a mini soccer ball, larger than the small hard plastic ball used outdoors. While the larger size gives the new player confidence in learning to hit the ball, proper technique is necessary because the arena game is played on a dirt surface with the ball bouncing on the uneven surface and off the arena wall.
Arena Polo is played either indoors or outdoors, days or nights under lights and year around. Many clubs only play Arena Polo due to the high cost of maintaining grass fields and the smaller field size required. Arena Polo Clubs usually have a school/student program with horses for rent to student players learning the proper way to play the game, the rules of play and proper riding techniques.
Arena Polo is extremely exciting, with many changes in direction, fast action and a great spectator sport. Arena Polo can be an excellent introduction to polo and many of the players start in the Arena. With a qualified instructor, a new player can quickly learn proper hitting techniques and improve riding skills. With the constant change of direction of play in the arena, the player learns to recognize and properly enter the line and right of way, change from offense to defense and the need for team play. By playing in a confined arena, players feel more secure and with the ball rebounding off the arena walls, a player has more opportunities to hit the ball. Horses, while moving with quick bursts of speed, are more under control. Players are taught proper team play, how to hit a pass to teammates, and to learn to anticipate opponent's plays and strategies.
The Outdoor game is played on a much larger surface with dimension of 160 yards wide (boarded) and 300 yards long, which makes it ten times the size of an official arena or ten football fields. Arena boards encompass the arena and are normally six feet high, whereas Outdoor, the boards are only eleven inches in height. Both applications assist in keeping the ball in play. There are other differences such as there are four players Outdoor and three players in the Arena. The Outdoor ball is made of plastic or wood and is 3" to 3 ½" in diameter. The arena ball should not be less than 4" to 6" in diameter. In the Outdoor Game, after each score, the scoring team changes goals and in the Arena Game, the team changes after each chukker. One of the major differences of the Outdoor Game is that the element of danger increases because of the increase in speed and the requirement to be more proficient as a horseman. More horses are required in that a normal Outdoor Game consists of six chukkers vs four chukkers in the Arena. Destination Polo Doug Barnes
You will find that Polo is a lifestyle whose members are a diverse family sharing a common love of respect for the athletic ability, power and stamina that define a polo horse. Whether you play Arena or Outdoor Polo, you will find the horses are alluring and seductive: To have played a great polo horse is an unforgettable experience that creates a habit-forming power over its rider. For more information about the Outdoor Game and its history, Destination Polo Doug Barnes about polo, I refer you to the USPA History which is located on their website...
GUIDE TO VIEWING POLO
What you'll see:
Two Referees - on horseback
Two Goal Judges - one stationed between the goal posts of each goal
Four Members of each team numbered 1 through 4
Many different horses - each player uses a fresh horse for each of 6 chukkers
Incredible equestrian skills, lots of galloping and major league action
HOW THE GAME IS PLAYED
Generally, the game is governed by two basic concepts; 1. polo is a team sport with each of the 4 team mates (or 3 for Arena Polo) playing a specific position yet supporting the entire team in both offense and defense, and 2. the "line of the ball." The line of the ball is created once the ball is struck and does not change until it is struck again, sending the ball in a different direction. The line of the ball is used in many ways, most importantly to act as an imaginary buffer to avoid collisions when two or more players ride to the ball for strike. The players much hit the ball to their right side (the "off side") and may not cross the line of the ball if doing so would cause a hazardous situation.
SCORING AND FOULS
A score is achieved when the ball crosses the goal line between the goal posts of the opposing team. Fouls are given for infractions of the rules governing field of play, usually for hazardous riding or improper us of the mallet. The umpire can award anything from a free goal to a free hit from a determined distance when a foul is called.
Chukker - a 7 minute period; six per game with 3 minutes between chukkers
Off Side - the player's right side, where they hit the ball to
Line of the Ball - imaginary line created by the ball traveling from point to point set in motion by a strike
Throw In - the start of each game and each chukker where the umpire tosses the ball between both teams who are lined up at midfield facing the umpire