In the game of darts, a double is one of the scoring areas on the dartboard. The double scoring areas are the thin outer rings that surround the board. To score points on a double, a player must hit one of these outer rings, which will double the score for that section.
In addition to being a scoring area, the double also plays a critical role in the game of darts. In most darts games, a player must "double in" before they can begin scoring points. This means that the player must hit a double before they can start scoring points on any other section of the board. This rule is designed to add an element of strategy to the game, as players must carefully choose their shots to ensure that they can hit a double and begin scoring points.
Once a player has "doubled in," they can then begin scoring points on any section of the board, including the doubles, triples, and the bullseye. However, to win the game, a player must "double out," which means that they must hit a double scoring area to reach the exact score required to win the game. For example, if a player has a score of 40 remaining, they must hit a double 20 to win the game.