There are hundreds of poker variations but most follow the following basic guidelines.
Players are required to place a forced bet into the pot before the cards are dealt. The dealer will then shuffle the deck of cards, the deck is then cut and the appropriate number of cards for the variant of poker are dealt face down to each player.
After the players look at their hand the first round of betting begins. Players can decide to replace cards they have been previously dealt. After assessing their updated hand a player can either stay in the game, or fold (leave the game). If more than one person is left after this round of betting then another round commences, with players raising the stakes by putting more money into the pot - everyone must best equal amounts, if you cannot match the bet then you fold.
The rounds continue until there is only one player left, and this player wins the pot. If the only player left wins by everyone else folding then they are not required to reveal their cards (This is how you bluff). In a showdown for the pot all hands have to be revealed so they can be evaluated and the winner decided.
Winning Hands
Royal Flush: Five cards in sequence and of the same suit, starting from the Ace down to the 10.
Straight Flush: Any five cards in sequence and of the same suit.
Four of a Kind: A hand with four cards of the same rank.
Full House: A hand with three cards of one rank and two of another.
Flush: Five cards of the same suit.
Straight: Five cards in sequence. (The ace can be considered higher than the king, or lower than the two.)
Three of a Kind: Three cards of the same rank.
Two Pair: Two cards of one rank, two of another.
One Pair: Two cards of the same rank.
No Pair: Also known as a high card hand. The following example is considered "Ace high."