A narrow notch, groove, or opening, especially one for receiving something such as a coin or a letter. Also, a time slot on the broadcasting schedule or an assignment or position in a workplace.

A slot machine, or poker machine, is a gambling machine that takes coins or paper tickets with barcodes and spins reels to generate combinations of symbols. The machines are regulated by law and may be only operated in specific locations, such as bars or hotels. Most modern slots use random number generators to produce a variety of winning combinations. Historically, the machines were operated by pulling a lever or pushing a button, which activated one to three of four reels that could be marked into horizontal segments by various symbols. Symbols commonly used include stars, card suits, numbers (7 is a popular choice), bells, and various pictured fruits—cherries, lemons, watermelons, plums, and oranges.

In recent years, research has uncovered additional reasons why players enjoy slots. For example, arousal produced by the game’s periodic rewards helps them focus their attention and avert negative thoughts and memories, which can be associated with painful emotional experiences. Dixon and colleagues have found that problem gamblers who experience this mental state during play are more likely to rate their slot-machine experience as enjoyable than nonproblem gamblers who do not report experiencing dark flow. This suggests that arousal accounts for positive affect variance that is distinct from reward reactivity.