Curling is an Olympic sport in which teams of four throw 42-pound stones down a 150-foot sheet of ice. The sport of curling originated in Scotland, in which teams would throw small stones along the surface of frozen lakes and were swept with brooms made of corn bristles.
As the game of curling evolved in Scotland, the stones used to play the game became larger and were eventually fitted with handles. The sport continued to spread across Europe and later expanded into North America during European immigration in the 1800s.
The sport of curling may seem complex at first, but is rather simple. Teams of four players alternate throwing eight stones each, for a total of 16 stones thrown. The throwing of these 16 stones makes up an end. In a game of curling, usually, eight to ten ends are played (eight ends at the recreational level and 10 ends at the national/international level).
The objective of the game is to score more points than your opponent by throwing stones into the house, a series of concentric circles that are one, four, eight, and 12 feet wide. Whichever team's stones are closest to the center of the house, the button, will receive a point per stone that is closer than their opponent's stone that is closest to the button. The team with the most points at the conclusion of eight (or ten) ends wins the game.
Since then, the sport of curling has been rapidly standardized by the World Curling Federation, the international governing body for the sport of curling. They often make modifications to rules and regulations of curling, the most recent one being the modification of the Free Guard Zone Rule. Formerly, a guard could be removed from play after the first four rocks of the end were thrown. Now, a guard can be removed from play after the first five rocks of the end are thrown.