Blackjack is most often played with six decks of French cards (the number of decks may vary from 1 to 8), with each deck consisting of 52 cards - from a two to an ace in four suits (including two black - spades and clubs and two red – hearts and diamonds).
Cards from 2 to 10 have their face value, the cards from jack to a king are worth 10 points and an ace is worth a variable value of 1 or 11. An ace has the ability to create so-called "soft" combinations, which practically means that, given an ace and 8, the total can be either 9 or 19. This is called "soft 19". This value of the combination at the start of the hand counts as 19, but if a player draws another card and the sum exceeds 21, the value of the ace is reduced to 1.
The combination of an ace and a 7 is called "soft 18". It has a value of 18, but if the player decided to get another card and got an eight, the value of the ace would automatically become 1, making the entire hand worth 16.
Blackjack is played against the dealer, with the player aiming to obtain a higher value hand than the dealer, but not exceeding the value of 21. If you exceed 21, the game is over regardless of the sum the dealer has reached. If the dealer exceeds the limit of 21, the player wins, but only if the player hasn't exceeded the limit of 21 himself or herself.
The basic win in blackjack is in the ratio of 1:1. If the player gets a combination of an ace and a card worth 10, the player receives a reward for blackjack usually in the ratio of 3:2 (a bet of $1 wins $2.50, including the wagered $1).
There is also a rule that after reaching the sum of 17, the dealer does not draw another card. However, with soft 17 it's not automatic. This rule may be applied differently, so the dealer might draw another card or stand on soft 17, depending on the specific rules used in that game. If you play online, the instructions and rules in play are always displayed. Usually the instruction says "Dealer stands at soft 17" and "Blackjack pays 3 to 2".
If you happen to come across a type of blackjack, where the blackjack is rewarded at a ratio lower than 3:2 (mostly when playing with only one or two packs of cards), you should be aware that casino’s edge is much higher when this rule is applied.