It is entirely up to the player in blackjack if he wants to use a blackjack strategy. Many players will take up basic strategy because of how easy it is to use and how effective it is. Playing every hand in blackjack according to basic strategy can lower the house edge to 0.5%. But for some blackjack players that is not enough a strategy.

For those looking for a little extra edge they will usually turn to brick and mortar casinos and card counting because card counting cannot be done in online blackjack. But you can still try online at a site like William Hill, just so that you practice your card counting skills.

Card counting is a way of tracking what cards have been played to have an estimation of what is left in the deck still to be played. Once card counting blackjack players have an idea of what is left un-played in the deck they will base their wagering on that estimation.

Throughout an entire game of blackjack, these players will count the cards as they are played and discarded to manage their betting. This becomes a part of their betting strategy.
When counting cards, blackjack players tend to use one system or another. But like how basic strategy is the most widely used strategy for its ease and effectiveness, card counters in general will use the simplest counting system: the Hi-Lo System.

The Hi-Lo System assigns counting values to the cards, designating them as high, low or neutral cards. The breakdown is as follows:

2-6 are worth +1 and are considered low cards

7-9 are worth 0 and are considered neutral cards

10-Ace are worth -1 and are considered high cards

Well, now that you know that, let’s see how this counting system works, shall we?

In order for a count to be accurate, players must count all cards on the table including those of other players and the dealer. When making this count it is as simple as adding positive 1s and negative 1s. As the game progresses, players will gain a sense of what is left in the deck based on what their count says.

If their count is a strong negative number, like -3, it means that a good chunk of high cards have been played. This is because enough high cards have been played to send the count into the negative. This would be when blackjack players scale back on their wagering.

On the other hand, if the count goes strongly into the positive, like a +3, it means that a larger number of low cards have been played and counted and discarded. This implies that there are a greater number of high cards left. So counting players will then increase their wagering.

While card counting can give players an edge, it is not the key to beating the house. You can still lose a few hands here and there because counting cannot tell you exactly which cards are going to be dealt next—only what is likely.

One more thing on card counting in blackjack—while basic strategy is legal in casinos, card counting is not. You must be able to count in your head without alerting the dealer or any of the staff that you are counting. Getting caught can get you kicked out of the casino or even barred. And your winnings would not be accompanying you out the door.