The purpose of the game is to score points by getting stones closer to the house centre, or the "button", than the other team's stones. Players from either team alternate in taking shots from the far side of the sheet. An end is complete when all eight rocks from each team have been delivered, a total of sixteen stones. If the teams are tied at the end of the game, play continues for as many ends as may be required to break the tie. The winner is the team with the highest score after all ends have been completed (see Scoring below). A game may be conceded if considered unwinnable.
International competitive games are generally ten ends, so most of the national championships that send a representative to the World Championships or Olympics also play ten ends. However, there is a movement on the World Curling Tour to make the games only eight ends. Most tournaments on that tour are eight ends, as are the vast majority of recreational games.
In international competition, each side is given 73 minutes to complete all of its throws. Each team is also allowed two minute-long timeouts per 10-end game. If extra ends are required, each team is allowed 10 minutes of playing time to complete its throws and one added 60-second timeout for each extra end. However, the "thinking time" system, in which the delivering team's game timer stops as soon as the shooter's rock crosses the t-line during the delivery, is becoming more popular, especially in Canada. This system allows each team 38 minutes per 10 ends, or 30 minutes per 8 ends, to make strategic and tactical decisions, with 4 minutes and 30 seconds an end for extra ends. The "thinking time" system was implemented after it was recognized that teams playing aggressively (using draws and other low-weight shots which take more time for the stones to come to rest) were essentially being penalized in terms of the time they had available compared to teams which primarily use hits which require far less time per shot.