Polo is a team sport played outdoor on horseback in which the objective is to score goals against an opposing team. Riders score by driving a white wooden or plastic ball (size 3–3.5 inches, weight 4.25–4.75 ounces) into the opposing team's goal using a long-handled mallet. Goals are only valid if the scoring rider is mounted. The traditional sport of polo is played outdoors, and each polo team consists of four riders and their mounts. Play occurs in seven-minute periods, called chukkas. The full game is played over eight chukkas; however, depending on league rules, matches can also have four or six chukkas.
The modern indoor variant is called arena polo. In arena polo, there are 3 instead of four players on each team and chukkas are 7 1/2 minutes in length. The playing area is 300' x 150'.
Another modern variant is snow polo, which is played either outdoor or indoor on snow on a frozen ground or ice. Each team generally consists of three players and also the equipment differ from the sport of polo. Other variants include elephant polo, bike polo and Segway polo. These sports are considered as separate sports because of the differences in the composition of teams, equipment, rules, game facilities etc.