Poker is a card game that requires a lot of mental concentration. It also involves a certain amount of luck, although when betting is involved it becomes more of a game of skill and psychology.
Each player in a game of poker puts in a certain number of chips (representing money) into the pot at the beginning of the hand before cards are dealt. This is called the ante. Each subsequent player may call, put in the same amount as the previous player, or raise. A raise means that the player wants to put in more than the previous player and thus win the hand.
When a player has a good hand, it is often best to raise. This scares weak players into folding and will narrow the field. Similarly, raising when you have a bad hand can force players who need more cards in their hands to win into making bluffs that will likely be called.
Watch the other players to learn how they play and what their tells are. A tell is any unconscious reaction that a player makes that signals anxiety or excitement. It might be a twitch of the eyebrows or darting of the eyes, a change in the timbre of their voice, or anything else that gives away their hand. Paying attention to tells can keep you in the game longer and help you identify mistakes that your opponents make. This will allow you to punish them for their errors.