The casino house edge refers to the mathematical advantage that a casino has over players in games of chance. It is expressed as a percentage of each bet that the casino expects to keep over time. For example, a game with a 5% house edge means that, on average, the casino retains $5 for every $100 wagered. This edge ensures the casino's profitability while providing players with the thrill of gambling. Understanding the house edge helps players make informed decisions about which games to play and manage their bankroll effectively.