 The sections below provide a variety of more precise characterizations of the prisoner's dilemma, beginning with the narrowest, and survey some connections with similar games and some applications in philosophy and elsewhere. Particular attention is paid to iterated and evolutionary versions of the game. In the fomer, the prisoner's dilemma game is played repeatedly, opening the possibility that a player can use its current move to reward or punish the other's play in previous moves in order to induce cooperative play in the future. In the latter, members of a population play one another repeatedly in prisoner's dilemma games and those who get higher payoffs “reproduce” more rapidly than those who get lower payoffs. ‘Prisoner's dilemma’ is abbreviated as ‘PD’.