A narrow notch, groove, or opening, especially one for receiving something, as a key in a lock or a coin in a slot machine.

The slot is a tool used by airports to control aircraft traffic and prevent repeated delays caused by too many flights trying to take off or land at the same time. The slot, which is an authorization to land or take off during a specific time period, is distinct from air traffic control clearance and other types of approvals.

In a slot machine, the pay table lists the possible combinations of symbols that can earn credits based on their appearance on a winning line. Most machines have multiple pay lines, and some allow players to choose which lines to bet on before each spin. Those that offer the flexibility to select pay lines are called free slots, while those that always bet according to a fixed number of lines are known as fixed slots.

To play a slot machine, players insert cash or, in “ticket-in, ticket-out” machines, a paper ticket with a barcode. The machine then activates reels that spin and stop to reveal symbols, which may match a winning combination on the pay table. The payout amount depends on the type and number of symbols in a winning combination, and varies from machine to machine. Most slot games have a theme, and the symbols and bonus features are aligned with that theme.