Curling is a sport in which players slide stones on a sheet of ice toward a target area that is segmented into four concentric circles. It is related to bowls, boules, and shuffleboard. Two teams, each with four players, take turns sliding heavy, polished granite stones, also called rocks, across the ice curling sheet toward the house, a circular target marked on the ice. Each team has eight stones, with each player throwing two. The goal is to accumulate the highest score for a game; points are scored for the stones resting closest to the centre of the house at the conclusion of each end, which is completed when both teams have thrown all of their stones once. A game usually consists of eight or ten ends.

The player throwing the stone creates a curved trajectory, known as "curl", by gently rotating the stone as they release it. The stone’s path can also be influenced by two sweepers using brooms or brushes, who move alongside it and sweep the ice in its path. Sweeping reduces friction, allowing the stone to travel further and in a straighter line, with less curl. Strategy and teamwork play a crucial role in selecting the optimal path and final placement of the stone, and the skill of the players determines how accurately the stone follows the intended course.

Evidence that curling existed in Scotland in the early 16th century includes a curling stone inscribed with the date 1511 found (along with another bearing the date 1551) when an old pond was drained at Dunblane, Scotland. The world's oldest curling stone and the world's oldest football are now kept in the same museum (the Stirling Smith Art Gallery and Museum) in Stirling. The first written reference to a contest using stones on ice coming from the records of Paisley Abbey, Renfrewshire, in February 1541. Two paintings, "Winter Landscape with a Bird Trap" and "The Hunters in the Snow" (both dated 1565) by Pieter Bruegel the Elder, depict Flemish peasants curling. Scotland and the Low Countries had strong trading and cultural links during this time, which is also evident in the history of golf.

The word curling first appears in print in 1620 in Perth, Scotland, in the preface and the verses of a poem by Henry Adamson. The sport was (and still is, in Scotland and Scottish-settled regions like southern New Zealand, as well as in Canada) also known as "the roaring game" because of the sound the stones make while travelling over the pebble (droplets of water applied to the playing surface). The verbal noun curling is formed from the Scots (and English) verb curl, which describes the motion of the stone.

Kilsyth Curling Club claims to be the first club in the world, having been formally constituted in 1716; it is still in existence today. Kilsyth also claims the oldest purpose-built curling pond in the world at Colzium, in the form of a low dam creating a shallow pool some 100 by 250 metres (330 by 820 ft) in size. The International Olympic Committee recognises the Royal Caledonian Curling Club (founded as the Grand Caledonian Curling Club in 1838) as developing the first official rules for the sport. However, although not written as a "rule book", this is preceded by Rev James Ramsay of Gladsmuir, a member of the Duddingston Curling Club, who wrote An Account of the Game of Curling in 1811, which speculates on its origin and explains the method of play.

In the early history of curling, the playing stones were simply flat-bottomed stones from rivers or fields, which lacked a handle and were of inconsistent size, shape, and smoothness. Some early stones had holes for a finger and the thumb, akin to ten-pin bowling balls. Unlike today, the thrower had little control over the 'curl' or velocity and relied more on luck than on precision, skill, and strategy. The sport was often played on frozen rivers although purpose-built ponds were later created in many Scottish towns. For example, the Scottish poet David Gray describes whisky-drinking curlers on the Luggie Water at Kirkintilloch.

In Darvel, East Ayrshire, the weavers relaxed by playing curling matches using the heavy stone weights from the looms' warp beams, fitted with a detachable handle for the purpose. Central Canadian curlers often used 'irons' rather than stones until the early 1900s. Canada is the only country known to have done this, while others experimented with wood or ice-filled tins.

Outdoor curling was very popular in Scotland between the 16th and 19th centuries because the climate provided good ice conditions every winter. Scotland is home to the international governing body for curling, the World Curling Federation in Perth, which originated as a committee of the Royal Caledonian Curling Club, the mother club of curling.