Olympic curling consists of two events: men’s curling and women’s curling. It became an official Olympic event at the 1998 Nagano Winter Olympic Games. Despite the example given by Marge and Homer Simpson, mixed doubles curling was not an official event at the 2010 Vancouver Winter Olympic Games.
The sport of Olympic curling is played on a long, narrow sheet of ice by teams of four. Each curling team has four members: the lead, second, third (or vice-skip), and skip, who is also the captain of the team. Each member of the team delivers two heavy granite stones to the opposite end of the ice, alternating with the corresponding member of the other team. The skips are responsible for deciding the shots to be played. In most cases the skips of the two teams also shoot last, which gives them the hardest shots. On some teams, the skips might shoot second or third instead. The last rock of all is called the ‘hammer.’
The goal of Olympic curling is to end up with a rock as close to the centre of a marked target area, or ‘house,’ as possible. (A detailed description of curling ice and its markings is available here.) Three types of shots are used to accomplish this goal: the guard, the draw, and the takeout. The free guard zone rule does not allow most takeouts until each team has delivered at least two stones. Only stones which land between the second hog line and the back line are in play. A stone must also be released by the person delivering it before it passes the first hog line. Stones that fall short or go too far are out of play and removed from the play area.
Curling brooms are used to sweep the ice in front of a moving rock, temporarily melting the ice and decreasing its friction. This decreases the curl of the rock. It doesn’t make the rock go faster, but it keeps the rock from slowing down as much. The team delivering the rock may sweep the ice in front of the rock up to the halfway point of the house. Past that point, the other team may sweep instead, usually to make the rock go out of play. Neither the sweepers nor any other member of the team are allowed to touch a rock in play.
An Olympic match consists of ten ends. An end is complete after each team has thrown all of its eight rocks. If at the end of a match the score is tied, one or more extra ends are played until the tie is broken. Each team has 73 minutes to complete all its throws, with ten minutes of additional playing time per extra end. Two 60-second timeouts are allowed in regulation play, with one extra timeout per extra end.
Scoring takes place at the conclusion of each end. The stone which is both in the house and closest to the center of the house counts for one point. After that, every other stone in the house belonging to the same team, so long as it is closer than every stone of the opposite team, counts for an additional point. Only one team can score per end. Last rock advantage (the hammer) in the next end always goes to the team which did not score in the previous end.
If one team is so far behind another that it is very unlikely to catch up, they may concede after eight completed ends of play. A team may only concede a game when it is their turn to deliver a stone.
The Olympic curling tournament format is a round robin played among qualifying teams. The host country qualifies automatically. Other teams qualify by earning the most points during the previous three World Curling Championships. Although Scotland, England, and Wales each compete independently in international curling, only the Scottish team can earn Olympic qualification points for the United Kingdom. The top nine teams, along with the host country, will compete in the Olympics.
During the round robin, every team plays every other team once. The four teams which score the highest in the round robin proceed to the semi-finals. The winners of those games play for the gold and silver medal, while the losers play for bronze and fourth place.