The origins of curling date back to the 16th century in Scotland, where the game was played on frozen lochs and ponds. The modern game evolved during the 20th century, aided in large part by the move indoors through the use of refrigerated ice. Curling became a full medal Olympic sport in 1998 and today over a million curlers are on the ice during the season. Curling is a team sport played on ice with 42-pound granite stones. The size of the playing surface (a "sheet") is 138 feet long by approximately 14 feet wide. Target areas, known as 'houses', are located beneath the ice at each end of the sheet, thereby allowing play in both directions.
A curling team consists of 4 players, called the 'Lead', the 'Second', the "Third" (or Vice-Skip), and the "Skip." The Skip is the captain and chief strategist for the team. All four members, beginning with the Lead and ending with the Skip, deliver two stones each during an 'end' (similar to an inning in baseball).
In curling, each player delivers his/her stones each end, alternating with their counterpart on the opposing team. After all stones are thrown, the team with stones closest to the center of the house scores points for that end. The point total is determined by the number of stones closer to the center of the house than the nearest stone of the opposing team. A game normally consists of 8 ends, which takes approximately two hours to complete. Sometimes competitive play requires 10-end games and an extra end if teams are tied at the end of regular play.
While the stone is traveling down the ice, the delivering team's players are allowed to sweep in front of the stone. Sweeping is done with a broom specifically designed for curling. The sweeping action melts the surface of the ice slightly, which can alter the speed and the direction of the stone.