Poker is a card game in which players place bets against one another based on the value of their hand. Various forms of the game exist, with some being suitable for only two players while others can accommodate more than 10. In general, the object is to win the pot (i.e., the sum of all bets placed during a single deal). This may be achieved either by having the highest-ranked poker hand or by making a bet that no other player calls.
In most poker games chips (representing money) are used to make bets. Players may also choose to use real cash, though this is less common. During a betting round, each player in turn must place chips into the pot equal to or greater than the amount bet by the player before him. In fixed-limit poker, a player may raise his bet only by an amount that is no more than the limit established for that betting interval.
The first card dealt to each player is called the flop. After the flop is exposed, everyone gets another opportunity to bet again or to check and fold. In the third phase of the hand, the dealer puts a fourth community card on the table that anyone can use. Then comes the final stage of the hand, known as the river, where the fifth community card is revealed and everyone gets a final chance to bet or raise or fold.