Poker is a card game played by two or more players. Its rules vary, but all variations involve betting and the aim is to make a winning hand. The most common hand is a straight flush (five cards in order, such as 5-6-7-8-9). The higher the hand, the more likely it is to win. There are also other more exotic hands, such as a full house or a royal flush.
In addition to the usual betting, bluffing is an important part of the game. It can be used to raise the probability of a particular hand and thus improve one’s chances of winning, or it can simply be a way to distract other players from your real hand. In either case, it is not an insignificant part of the game, and the foundational 1944 book on mathematical game theory by mathematician John von Neumann and economist Oskar Morgenstern included poker as a key example of a game with an optimal strategy that relied heavily on bluffing.
Most poker games use a standard 52-card pack; some variants may add jokers or other wild cards. The suits are spades, hearts, diamonds and clubs, with the ace being high. The highest hand wins, although ties are possible. If there is a tie, the highest card breaks it. Some hands are considered ‘natural’ (high pair, three of a kind, straight), while others are not (fluffs and other non-naturals). There is also a high-card-only rule that can break ties in certain situations.