Blackjack is a card game played between a dealer and one or more players. The object is to draw cards that add up to 21 or as close to 21 as possible without going over (busting). Aces count as either 1 or 11, and the picture cards (Jack, Queen, King) count as 10. The dealer gives each player two cards and then deals himself two cards face down. Players may also place side bets on their hands, including insurance, which pays 2-1 if the dealer has a blackjack.

In the last two decades or so, blackjack side bets have become extremely popular. There are hundreds of different kinds of side bets that can be placed at the same time you place your main wager. These include betting on getting a pair as your first two cards, betting that the dealer will have a certain poker hand with his up card, and more. While these side bets can make the game more exciting, they also increase the house edge and make it harder for a skilled card counter to beat the dealer.

The game of blackjack is generally played with a deck of cards that has been shuffled and cut at about one-fifth of their original size. This prevents knowing the precise number of cards of a given value in the deck, which makes it very difficult to develop a mathematically correct strategy for the game. However, approximations can be used that by-pass the difficulty of probability computations and still provide an optimal strategy for blackjack. This approach was developed by a quartet of U.S. Army mathematicians in 1956 who became known as the Baldwin group.

Another change to the game that increases the house edge is reducing the payout on blackjacks to 6 to 5. While this may sound like a small change, it can really add up over time and makes the game unprofitable for serious players.

After the players have finished making their hands, the dealer will check her hole card (using a special viewing window in the table). If she has a ten underneath, she has a blackjack and wins everyone’s original bets. She will then take any insurance bets and the game continues as usual.

If the dealers doesn’t have a blackjack, the players will push the hand (get their original bet back). In this case, the dealer collects the cards, shuffles them, and starts a new round. This is a big mistake for players, as it decreases their chances of winning against the dealer. It is best to stick with games that pay 3:2 for blackjacks. You can find these games at most online casinos. Some of these sites also offer mobile casino versions of blackjack, which are easy to use on the go!