Poker is a card game in which players wager chips that represent money. The goal is to make the highest-ranking hand, and to win a pot (the total amount of bets placed). Poker can be played in a cash or tournament game, but the rules are the same. In a cash game, the players must each ante a set amount of money to get their cards; in a tournament, the participants contribute to a pool of prize money that they compete to win.
Once everyone has their two cards, a round of betting begins. Each player can either check (passing on betting), raise (putting more chips into the pot than their opponents must match), or fold.
A second card is dealt face up, and another round of betting starts. If a player has a strong hand, they can bet at this point to force weaker hands out of the pot. If a player has a weak hand, they can either call the bet or fold.
Maria Konnikova, a psychologist and writer, has written a book about how she uses the game to improve her decision-making. She says that poker gives her an opportunity to practice making choices under uncertainty in a low stakes, controlled environment. She believes that this type of practice is important because life is full of unpredictable variables like health problems, job loss, and relationships.