A slot is an opening, groove or gap in which a printed circuit board can be inserted. A slot can also refer to a position on the face of a machine that allows for insertion of a coin or paper ticket. Slots can be found in a computer as well, where they are called expansion slots, although they should not be confused with bays, which are sites for disk drives in a machine.

Most slot machines are based on chance, with the player inserting cash or, in “ticket-in, ticket-out” machines, a paper ticket with a barcode into a designated slot on the machine. The reels then spin and stop to rearrange symbols, and if the machine produces a winning combination, the player earns credits according to a pay table. Symbols vary, but classic symbols include stylized lucky sevens, bells and fruit. Most slot games have a theme that influences the design of the symbols and bonus features.

In American football and Australian rules rugby, a wide receiver who lines up close to the line of scrimmage (often called the boundary). A slot receiver can stretch defenses vertically off pure speed, running shorter routes on the route tree, such as slants. The slot is especially important in pass-heavy offenses, where the quarterback needs receivers to catch the ball away from coverage.