A narrow depression, groove, notch, slit, or aperture, especially one that receives and admits something, as a keyway in machinery or a coin slot in a vending machine. Linguistics. a position within a grammatical construction into which any of a number of morphemes or morpheme sequences can fit.

Traditionally, slots are random-determination machines where players deposit money and then pull a lever to spin the reels. They can include different symbols, such as stars, card suits (aces, kings, queens, and jacks), bars, numbers (7 is a popular choice), or various pictured fruits (cherries, plums, watermelons, oranges, lemons, and so on). A winning combination pays off according to the odds of hitting the jackpot.

Slots account for the bulk of casino profits, and gaming managers go to great lengths to keep them happy. One tactic is to lower what’s called the house edge, which is calculated as the long-term difference between how much was wagered versus how much was paid out.

But raising that house advantage puts casinos at risk of losing customers. If players can detect an increase in house edge, they may choose to play at another venue, and this hurts operators. To avoid this danger, casino operators are reluctant to increase the house edge of their slot games. Instead, they rely on research into player behavior, such as scrutiny of existing games by companies like ReelMetrics or SG’s newly launched SG Connect. These systems are designed to provide data on how often a game is played and how long players stay at it.