The laws of the country, according to regulatory change. You can play from 18 years and in some countries from 21 years as the United States. You can not play in all states. Some sites do not accept American players, such as Microgaming, but you will find the RTG for the most part, accept without problems. Read the conditions of different online casinos.
Firstly, the player places his bet in the circle. The dealer will then deal two cards, face up to each player and two to himself, one face, one returned.
King, Queen, Jack and 10 have a value of 10. Aces count as 1 or 11, as requested by the player. Other cards, 2 to 9 have the value of their number.
Having a Blackjack is to have 21 points. If the player shoots two aces and another 10 value card, the player has Blackjack and receives a gain of one and a half times his bet unless the dealer also has blackjack. The Player not having Blackjack may continue to draw cards and try to get as close as possible to near 21. Never exceed 21, because then you lose your bet.
The dealer must hit on all totals of 16 or lower. The dealer must stand on all totals of 17 or more.
Blackjack is purely a game of chance. It is not necessary to count cards, they are anyway brewed each round.