A narrow notch, groove or opening, as in a keyway in machinery or a slit for a coin in a vending machine. The term is also used to describe a position within a series or sequence, as in “an important slot in the physics of quantum theory.”

In air traffic, a slot is an authorization for a planned aircraft operation, such as a takeoff or landing, at a specific time and date. Slots are primarily used to manage air traffic at busy airports, and help prevent repeated delays caused by too many flights trying to take off or land at the same time.

There are several different types of slot games available, with varying return to player percentages, volatility levels and maximum win values. Some slots are progressive, with a jackpot that increases over time as players play. Others have stacked symbols, which increase the chance of a winning combination by covering multiple positions on each reel. Some slots also offer Wilds that act as substitutes for other symbols or can open bonus levels and other game features.

To play a slot machine, the player inserts cash or, in “ticket-in, ticket-out” machines, a paper ticket with a barcode. The machine then activates the reels, which spin and stop to rearrange the symbols. If the player matches a winning combination, the machine pays out credits according to the pay table. Most slot games have a theme and feature classic symbols such as fruits, bells and stylized lucky sevens.