Poker is a card game based on a high-ranking hand system. There are many rules to the game, but most all of them apply to the many variants that have been produced over the years.
The best way to get started in online poker is to learn the way different poker games are played. One very popular variation is Draw Poker, with the most common of these being Five-Card Draw. In this variant, each player at the table receives a full hand of five cards at the beginning of the game. There are usually three rounds in which a player may remove cards from his or her hand and replace them with other cards drawn from the deck.
Then you have the option to bet on your new hand or check (which is the equivalent of betting zero on your turn) or fold. When the number of specified rounds is over, everyone remaining at the table shows his or her hand, and the winner takes all of the chips.
Another variation that appeals to many players is Stud Poker, which contains the popular Five-Card Stud variant. At the beginning of the game, each player at the table is dealt one card face-down and one card face-up. The players then bet on their current two-card hand and then the dealer deals another card face-up to each person playing, continuing this for the whole hand. Since the other player at the table can see what four of your cards are, the betting and playing strategies are much different than games where all five cards are held in your hand, unseen to others.
A common variant that is very similar to Stud is called Community Card Poker, in which the face-up cards are shared by all players at the poker table. The most popular type of this game is Texas Hold Em, and is one of the most-played card games ever. In this game type, each player is dealt two cards face-down at the beginning of the game. For the remainder of the rounds, one card is dealt to the community hand face-up, while each player gets an option to bet on the combination of the cards held in their hand and the cards in the community hand. At the conclusion of each game, the winner takes all of the chips.