Edge

The house edge is the casino's built-in statistical advantage — the percentage of each bet it expects to keep over the long run. It varies widely by game: blackjack with perfect Basic Strategy runs about 0.5%, European roulette 2.7%, American roulette 5.26%, baccarat's banker bet 1.06%, and slots anywhere from 2% to 15%. Worked example: betting £10 a spin at about 60 spins an hour on European roulette (2.7% edge), your expected loss is roughly £10 × 60 × 0.027 = £16.20 per hour. Move to American roulette (5.26%) at the same pace and stake and it becomes about £31.56 per hour — nearly double, entirely because of the extra double-zero pocket. The single added number doubles the cost of play. The house edge matters because it explains, more directly than anything else, why the longer you play a negative-EV game, the more likely you are to lose. It is the engine behind a casino's reliable profit. The common mistake is believing skill can overcome the edge in pure games of chance. It cannot — strategy can only reduce it, as Basic Strategy does in blackjack, never erase it — and chasing losses against a fixed edge only deepens them. Because the edge is unavoidable in the long run, the sensible response is to set time and money limits before playing. See also Expected Value, RTP, the Hold and Variance.