Despite their random nature, slot machines still produce a predictable payout: the machine keeps a certain percentage of the money you wager. In other words, if you bet a nickel on a twenty-payline machine, and you win on only one payline, you would only lose 50 cents. The machine would still report the payout as a “net winner.” Interestingly, multiple scientific studies have shown that our brains treat near-miss results as actual wins.

Early slot machines featured a horizontal line on the front, representing a payline. The player would insert coins, and when matching symbols landed on that line, they would win the prize amount. Since these machines were designed for profit, they often replaced the prizes with candy or other small prizes. In the 1980s, manufacturers began to incorporate electronics into their machines and programmed them to give particular symbols more weight. As a result, the likelihood of losing a symbol became disproportionate to its frequency on the physical reel. In some cases, a symbol could take up to three stops on a multiple reel.

The main difference between a multi-coin/multi-line machine and a classic single-coin machine is the number of paylines. Multi-coin/multi-line machines allow players to select how many coins to put in each line. The traditional single-coin machine is becoming less popular, while multi-coin machines offer a larger number of paylines and more chance of winning. Oftentimes, a player can choose a bonus feature, which allows them to access additional winning combinations.