A statistical calculation of the expected player loss relative to the initial amount bet. The House edge is the casino's inbuilt advantage.
As such, it is a good measure to base player expectations over time, but falls short of being a precise forecast. A 0.5% House Edge in Blackjack, for example, means the player should expect to lose $0.5 for every $100 bet. The calculation does not, however, take in additional money bet (doubling, raising) or ties.