In game theory

Game theory

Game theory is a mathematical method for analyzing calculated circumstances, such as in games, where a person’s success is based upon the choices of others...

 a move by nature is a decision or move in an extensive form game

Extensive form game

An extensive-form game is a specification of a game in game theory, allowing explicit representation of a number of important aspects, like the sequencing of players' possible moves, their choices at every decision point, the information each player has about the other player's moves when he...

 made by a player who has no strategic interests in the outcome. The effect is to add a player, 'Nature' whose practical role is to act as a random number generator. For instance, a game of Poker

Poker

Poker is a family of card games that share betting rules and usually hand rankings. Poker games differ in how the cards are dealt, how hands may be formed, whether the high or low hand wins the pot in a showdown , limits on bet sizes, and how many rounds of betting are allowed.In most modern poker...

 requires a dealer to choose which cards a player is dealt, the dealer plays the role of the Nature player

Fig.1 shows a signaling game which begins with a move by nature. Moves by nature are an integral part of games of incomplete information.