Poker is a card game of chance with elements of skill and strategy. It involves betting money in a communal pot — the “pot” — on a hand that you believe has a positive expected value. While the outcome of any given hand heavily depends on chance, the overall game is a contest between players’ decisions made on the basis of probability, psychology and game theory.
Each player is dealt 2 cards face-down and 1 card face up, then there’s a round of betting, started by 2 mandatory bets (called blinds) put into the pot by the players to their left. A third card is then dealt face up, this is called the flop, and another round of betting takes place. A good flop will force weak hands to fold and it will also raise the value of your pot.
The best hand wins. There are a variety of different types of hands, but the highest is five of a kind (five Aces beats four of a kind, five Kings beats five Queens, etc). If no one has a high hand then the highest single card wins.
To play well you have to understand the other players, and their tells. A tell is a unconscious habit of the player that gives away information about their hand, and can include facial expressions, body language, or a combination of these. This knowledge helps you read your opponents, and make better decisions about how to play your own hand.