When most people think of a casino, they imagine one of the megaresorts in Las Vegas—a glitzy hotel and entertainment complex that brims with neon lights, fun, and games. But a casino is actually much more than that. The Merriam-Webster dictionary defines it as “a building or room used for social amusements, especially gambling.” And while many casinos are massive resorts, others are smaller businesses defined more by the types of gambling they offer than by glitz and glamour.

According to Gemini Research, when asked which casino games they enjoyed playing most, the largest portion of respondents chose slot machines. They were followed by card games and table games like blackjack and poker, with bingo and keno garnering only a small percentage of the overall response. The report also indicated that casinos earn a significant portion of their income from these machines—ranging from 65 to 80 percent in states that cater primarily to locals to 50 percent in the Las Vegas Strip, where high-roller action skews the results toward table games.

Beneath the twinkly lights, boisterous noise, and free drinks, casinos are built on a bedrock of mathematics, engineered to slowly bleed patrons of their cash. And while some mathematically inclined minds have figured out ways to beat the house edge in games of skill, such as blackjack and poker, it is generally agreed that for most gamblers, luck—and not their skill—is the primary driver of their outcome. For that reason, it is important to set a fixed amount of money that you are willing to lose before entering the casino.