Blackjack, originally a french game, is one of the most popular cardgames in the world.
Blackjack is played with one or more decks of cards. (1 deck=52 cards).

At the beginning of the game, the dealer shuffles the cards and offers them to a player to cut. After each player has placed their bets (minumum and maximum bets are established by the casino), the dealer gives each player and himself two cards. The dealer's first card is face up, the second one is face down.

The object of the game is to draw cards that total as close to 21 as possible, without exceeding it.
Each player gets his turn, starting from the dealers left.
Face cards (J,Q,K) count as 10, Aces count as 1 or 11, all other cards count as face value.

If the first two cards dealt to the player or to the dealer consist of an Ace and a 10 value card (10,J,Q,K), they constitute a "Blackjack". If the player has a "Blackjack" the dealer will pay one and a half times the original wager (3 to 2).

To improve their hands, players may ask for additional cards (Draw or Hit) or Stand.
After each player is satisfied with his hand (noone is asking for more cards), the dealer will turn up his card. If his total is 16 or less, he must draw cards until his total is 17 or more. If the dealer receives an Ace, he will count that Ace as 11, if his total is 17 or more without exceeding 21.

If the player Busts (his total is higher than 21), the dealer will collect the bet and the cards.
If the dealer Busts and the player not, the player wins his bet, even money.
If neither the dealer nor the player Busts, the person with the higher total wins.

If the player and the dealer have the same total without busting, it is called a "Push" - no money changes hands.

If the player's first two cards are the same numerical value, the player may treat these cards as the inital first card in two separate hands - Split. The player receives automatically a second card, and he may elect to Hit or Stand. Exception: split Aces get only one card.

If the dealer's up card is an Ace, an additional bet is allowed before the draw. The player may put up a side bet against the dealer's potential blackjack, equal at most to half his original bet - Insurance. After the player has decided whether or not to do this, the dealer checks his hole card. If the dealer does not have a Blackjack, the insurance bet is lost and the play continues. If the dealer has a Blackjack, the side bet (insurance) wins twice its amount (2 to 1).

However rules are different in certain casinos. Some casinos will allow doubling only on 9,10 and 11. In most North-American casinos the dealer gets two cards, in the Carribean, Europe and Asia the dealer has only one card. Almost all the casinos limit the number of splits and the number of hands one player can play. In certain casinos if you split Aces and you receive an Ace, you may split again.
The number of decks the game is played is different in every casino. In Las Vegas you can find single or double deck Blackjack tables, but if you go to Europe most casinos playe with 6 decks.
If you find yourself in a situation where something is not allowed, don't worry: it's just a house rule.
Yes you may tip the dealer! He/she'll be nicer to you, even help you out.