House edge represents the mathematical advantage that a casino maintains over players in any given game. Expressed as a percentage, it indicates the average amount of each bet that the casino expects to win over time. Understanding house edge is fundamental to comprehending why casinos remain profitable institutions while individual players face long-term disadvantages.
The house edge is built into the rules and payouts of every casino game. For example, in European roulette, the single zero gives the casino approximately 2.70% house edge, while American roulette with both zero and double-zero increases this to 5.26%. These seemingly small percentages compound dramatically over thousands of hands or spins, ensuring the casino's profitability.
Different games offer vastly different house edges. Some games like blackjack can be played with house edges below 1% when using optimal strategy, while others like slot machines may have house edges exceeding 10% or more. Knowledgeable players can reduce the house edge through strategic play and game selection, though they cannot eliminate it entirely.