In curling, the playing surface is known as the sheet, as curlers play on a long sheet of ice. A curling sheet is 150 feet long and 14 feet, 2 inches wide. On both ends of the sheet, there is the house which contains four concentric circles called:
You will notice that the colors of the houses vary. This is to easily distinguish between the start and end areas of each of the circles. Running along the long sides of the sheet are the sidelines. If a stone reaches a sideline, it is out-of-play. Parallel to the sidelines, but in the middle of the sheet, it the centerline. In front of each house is a hog line. When a curler is shooting he must release the stone by the first closer hog line, and the stone must pass the second hog line completely to be in play. Directly behind the houses is the backline. After a stone fully crosses the backline, it is out-of-play.