You never play against other players, but always only at the online casino. All cards in blackjack game do it, except the jokers. It counts each card for its own value and his jack, queen and king worth 10 points. An ace counts as one or 11 points, and this depends on the number of points you have already. When sharing begins, you get two cards on the table. With these cards you can reach the maximum of 21 points at one time.
Then you have instant blackjack and you always win. You get 2.5 times your bet is paid back at a blackjack. Do not you have an instant blackjack then you have several options. You can take an additional card and hope to get closer to 21 points, but can also stop the same and see what the dealer has cards. Do you twice a card with the same value, you may split the hand.
To do this, you place the same bet again and have the chance to win. 2 hands in blackjack, the dealer is more limited in his choice and therefore has only two options. At 17 points or more, the dealer must always stop. If the dealer has 16 points or less there will always be a card to be taken. If you make sure you always have more points than the dealer, but not more than 21, then the chances are that you can go win playing blackjack.