A slot (plural: slots) is a narrow aperture or groove, especially in a door, wall, or other surface. Slots can also be found on machine parts such as pulleys, spindles, and drums.

In a slot machine, players insert cash or, in “ticket-in, ticket-out” machines, a paper ticket with a barcode, into a designated slot. The machine then activates a series of reels to rearrange symbols. When the symbols match a winning combination, the player earns credits according to the paytable. Symbols vary, but classic symbols include fruits, bells, and stylized lucky sevens. Most slot games have a theme, and the symbols and bonus features are usually aligned with that theme.

Slot games are the largest source of casino profits, making up more than 85 percent of industry profits. Yet they have a reputation as being high-stakes, high-pressure games of chance where fortunes can be won or lost in the blink of an eye.

A slot receiver can create mismatches downfield and be a big-play threat for the offense, as they are often used on short routes that can be challenging for defenses to cover. Moreover, the offensive scheme may be designed specifically to target the slot receiver.