Blackjack is based decks of 52 playing cards. If you have ever had a statistics and probability course in school, you've probably dealt with the probability of drawing one particular card from the deck. Using the same principles it's possible to determine the odds of winning or losing any particular blackjack hand.

In any casino blackjack, the house has the edge. That means over time, the casino is going to win more hands than the player. Eventually the casino will win. The casino gets this edge primarily because the player goes first. The player has a chance to bust before the dealer.

Basic blackjack multi-deck strategy is designed to minimize the house edge. If you adhere to strict rules regarding what action to take based on the dealers up card and your hand total, you can reduce the house edge to it's bare minimum. Basic strategy has already worked out which action will statistically be the best action for the player. Basic strategy does not guarantee you will win every hand. But over a long enough period of time you will perform better if you adhere to the basic strategy. Keep in mind that no matter how well you play the basic strategy, the house still has the statistical edge.

Card counting is the next step beyond basic strategy. The dealer must hit below 17. This means that having low value cards in the shoe is statistically beneficial to the dealer. The dealer has an advantage when it is likely that he will draw a low value card. Conversely, the dealer is at a disadvantage when there are more ten value cards in the shoe. The dealer is more likely to bust when hitting below 17. Statistically the player has an edge of the house when there are more 10 value cards in the shoe.

Card counting seeks to take advantage of knowing when there are more ten value cards in the shoe. Blackjack has a "history" in that as cards are played from the shoe they move to the discard pile. So, if you know that more low value cards have already been played, then you know that there must be equally many ten value cards remaining in the shoe. Therefore you know that you have an advantage over the casino. When you realize you have the statistical edge, you raise your bet accordingly. You wager more when the cards are in your favor.

All card counting systems rely on keeping a "running count". The running count represents the history of the game. Basically, every time you see a low value card played, you add one or more points from the running count. Every time you see a ten value card (or an ace) you subtract a point. A positive running count is signals that more low value cards have been played, and that there are equally many ten value cards in the shoe. In the most basic systems, that's all you need to do. You need to know when to add or subtract points, and you must keep an accurate running count in your head.

Please note that that "history" of the game is lost whenever the dealer shuffles. All cards are added back into the shoe, so the game starts over. At this point you must start your running count over at its initial value.

A card counter plays blackjack betting the table minimum and keeping the running count. You increase your wager on when the count signals you have an advantage. You wager more when you have the advantage to make up for all the hands you must play until you get a positive count. In some systems, the wager is proportional to number of the count. There is usually only a low and high bet in the basic systems. The minimum bet is usually the table minimum, and the maximum ten times that amount. Your maximum should also consider the size of your bankroll, because you must be able to last through losing many hands even when the odds are in your favor. Remember that a statistically advantage only becomes apparent over time.

Some systems like Hi/Lo system are balanced systems. A balanced system means that if you were to count accurately through the entire shoe, your running would start at zero and end at zero. A drawback to a balanced system is that the running count must be divided by the number of decks remaining in the shoe to get a "true" count. This presents two additional problems. One, you must perform this division in your head, and very quickly. Two, you must accurately estimate the number decks remaining in the shoe. You accomplish this by estimating the number of decks in the discard pile. Then you take the total number of decks in the shoe when you started and subtract the decks in the discard pile to give you the answer.

Fortunately the KO Count is an un-balanced system. This means if you were count through an entire shoe, you would not end with zero. To compensate, the KO Count begins with the running count at a value other than zero. The benefit is that you do not to calculate a true count. You only need to keep track of the running count. In my opinion, that makes it easier on the player. The main drawback is that you sacrifice some precision to achieve this level of ease. It's not much of difference, but you are going win more with a complex system. However, a simple system counted correctly is better than a complex system counted incorrectly.

The last piece of card counting is shoe penetration. Shoe penetration is how much of the deck will the dealer play until he shuffles. Penetration is usually represented by a ratio like 75%. In a game with 75% penetration, 3/4 of the cards will be played before shuffling. Penetration is important because if there is a low penetration percent, the dealer may shuffle before you reach a positive count. So, a player should always look for a game with the highest penetration. That means you are likely to get more positive counts and you are more likely to be able to take advantage of it.