In Blackjack (also called “21”) the Ace is worth 1 or 11, whichever is desired at the moment. All face cards (Jack, Queen, King) are worth 10 points, thus called “10-count” or “T” cards. All other cards are worth their number value. I.e., Q + 2 = 12. (Queen is a face card = 10; 2 = 2; thus the total 10 + 2 = 12.) The object of the game is to score as high as possible without going over 21. Therefore, 21 is the best score.
Every player starts with two cards, face up. The Dealer is dealt one card up (the “show” card) and one card down (the “hole” card). The players then go first, starting on the dealer’s immediate left. If you want another card you say “hit”, if not you say “stand”. If you score 22 or more, you “bust” or lose instantly. If your first two cards are a face card with an Ace, that is “Blackjack” and you win instantly, plus a “Blackjack bonus” of 50%. (I.e., if you bet $10, then with a “Blackjack” you win $15.) After the players are finished, the dealer draws until he reaches at least 17, then he must “stand.”
Splitting. If your first two cards have the same value, such as 8-8, you can “split” this into two hands, each hand starting with one 8 plus a second card from the dealer. If you split A-A, each new A-hand is not allowed a third card. A-A nonetheless is a good hand to split because you are likely to score 21 at least once. However this is not a “Blackjack” so the dealer can achieve a tie if he also reaches exactly 21.
Doubling Down. Before drawing a third card, if you feel the dealer has a weak hand, you can double your bet. You then must take a third card, and are not allowed more cards. Usually, you are allowed to double down only if you have 9, 10, or 11. Sometimes, you can not double down on 9, and this lowers your advantage. Other times, you can double down on any two cards. This raises your advantage because sometimes it is good to “soft-double” when you have A2, A3, A4, A5, or A6. (See the chart below.)
DAS or “doubling after splitting.” Sometimes this is allowed, sometimes not.
“Soft” hands. A soft count or a soft hand is when you have an ace with a numbered card or cards below 10. For example Ace + 4 is a “soft 15” because it can be either 15 or 5.
Insurance. If the dealer shows Ace, you can buy insurance for half your bet—then you win instead of losing if the dealer has Blackjack. However this is never worthwhile. You are betting $1 to win a possible $3, for a ratio of 4:12. Meanwhile the ratio of Blackjack-making face cards (10, J, Q, K) to all other cards is 4:13. This is like playing a double-zero Roulette-type game with only 13 numbers per zero instead of the usual 18—and double-zero roulette already is a terrible game for the player, so go figure.
Surrendering. If your hand is terrible, you can “surrender” if this is allowed. Then you only lose half your bet, but you always lose. Surrender is very helpful if you do not over-use it.
Notice that about 1/3 of the deck is face cards and 10’s. So if you assume the dealer’s hole card is a 10-count, and draw or stand accordingly, then usually this results in “basic strategy”. Also notice that the dealer is weakest when he shows a 6, because he must hit and is very likely to bust. With 4 or 5 showing the dealer also is weak, but slightly less likely to bust.
Basic Strategy. To maximize your long-range chances to win playing online casino blackjack, you must make every decision according to a disciplined “basic strategy.” This was determined decades ago using computer analysis.