A slot is a narrow notch, groove or opening such as a keyway in machinery or a slit for coins in a vending machine. It also refers to a time or place in which something can take place, such as an airport landing slot or a time slot on a schedule.

In a slot machine, a player inserts cash or paper tickets with barcodes (in “ticket-in, ticket-out” machines) into a designated slot and activates the machine by pushing a button or lever. The reels then spin, and if the symbols line up on the pay table, the player earns credits according to the amount specified in the table. Symbols vary by game, but classic symbols include fruits, bells, and stylized lucky sevens. Most slots have a theme, and the symbols and bonus features are aligned with that theme.

While the enjoyment of slots is attributed to several factors, researchers have emphasized the importance of context in explaining why some people enjoy gambling. For example, Dixon et al. (2019) found that problem gamblers who report having mindfulness problems outside of the gambling context endorse dark flow experiences more strongly during slots play than do control group players. The authors hypothesized that the contrast between mindful mentations in everyday life and attention-capturing reinforcement in the gambling context may contribute to this effect. However, more research is needed to test this hypothesis. Moreover, it is important to note that the joy experienced by some problem gamblers during slots play may not be entirely attributable to dark flow.