Poker is a card game in which players place bets, called chips, into the center of the table. The object of the game is to win a pot, which consists of all of the bets placed during a single deal. The pot can be won by having the highest-ranking poker hand, or by making a bet that no other player calls. Players may also bluff, betting that they have a better hand than they actually do.
There are hundreds of variations of poker, but all follow the same general principles. Poker is believed to have originated in the late 1700s or early 1800s, and it is not known whether it was inspired by any earlier card games or gambling.
Each round of betting in a poker game begins when all the players have received their two cards. The player to the left of the dealer antes a certain amount (the exact amount varies by game), and then places in additional bets to the pot as they see fit. Each player can call, raise the current bet, or fold their cards to stay out of the pot.
Ingo Fiedler and Jan-Philipp Rock from the University of Hamburg have studied the probability of a poker hand and found that it is not purely chance-based but requires a certain amount of skill. In fact, they found that the value of a poker hand increases in inverse proportion to its mathematical frequency. It is a fascinating paper, and it demonstrates that poker is indeed a game of skill.