Poker is a card game in which players place bets on the relative rank of their hands. The rank is determined by the odds (probability) of a hand, with higher-ranking hands winning more often than lower-ranking ones. Ties are broken by the highest unmatched cards (in a full house [three of a kind plus a pair]) or by secondary pairs (in a straight flush).
The game is played with chips; each player “buys in” for a minimum amount by placing white, red, and blue chips into the pot, with a white chip being worth one unit. The player who raises the most chips wins the pot.
In most modern games, each betting interval, or round, begins with the first player to the left of the button making some form of forced bet (the blind or ante). Each player then must decide whether to call that bet by putting in the same number of chips as the previous player; raise that bet, which requires the next player to put in more than the raised amount; or fold, losing the chips they have put into the pot so far and any further involvement in the hand.
While it can be tempting to limp into a pot, it is usually better to be aggressive and raise in order to price out the weaker hands. In addition, it is important to play the player, as a large part of poker strategy involves reading opponents through subtle physical tells and other behavior.