There are many ways that you an gain an upper hand when playing blackjack at the land based casino. They all fall under the title of advantage play. Essentially, you're finding ways to beat the casino's fixed advantage, also known as the house edge. The most well known method is card counting, though this is less relevant today than it was 20 years ago. Then there are things like trying to spot the dealers down card or marking the backs of the cards themselves. Finally, we have plain cheating.