Water polo is a competitive team sport played in water between two teams of seven players each. The game consists of four quarters in which the two teams attempt to score goals by throwing the ball into the opposing team's goal. The team with the most goals at the end of the game wins the match. Each team is made up of six field players and one goalkeeper. Excluding the goalkeeper, players participate in both offensive and defensive roles. Water polo is typically played in an all-deep pool so that players cannot touch the bottom.

A game of water polo mainly consists of the players swimming to move about the pool, treading water (mainly using the eggbeater kick), passing the ball, and shooting at the goal. Teamwork, tactical thinking and awareness are also highly important aspects in a game of water polo. Water polo is a highly physical and demanding sport and has frequently been cited as one of the most difficult sports to play.

The game is thought to have originated in Scotland in the mid-19th century as a sort of ""water rugby"". William Wilson is thought to have developed the game in 1870s. The game thus developed with the formation of the London Water Polo League and has since expanded, becoming popular in parts of Europe, the United States, Brazil, China, Canada and Australia.