Card counting is a blackjack strategy used to determine whether the player or the dealer has an advantage on the next hand. Card counters are advantage players who try to overcome the casino house. Card counting is simply using a system to keep track of the ratio of low cards to high cards. In Blackjack, it is favorable to the player when there are more Aces and 10 Value Cards (10’s, Jacks, Queens, and Kings) remaining in the shoe. So card counting is simply using a system to keep track of the ratio of low cards to high cards.

Here are the steps to count cards in blackjack:

1. Assign a value to every card.
2. Keep a "Running Count" based off of the values of the card dealt.
3. Use this information to calculate the count per deck or “true count”.
4. Change your bets as the true count rises.

Card counting is a long-term strategy, and keeping your 1 percent edge requires playing by the book game after game, while keeping count of what. Casinos have spent a great amount of effort and money in trying to thwart card counters. Countermeasures used to prevent card counters from profiting at blackjack include decreasing penetration, the number of cards dealt before a shuffle, banning known counters from playing blackjack, all games, or entering casino property (trespassing) .