A narrow slit or opening, as in a door, a window, or a machine. Often used to refer to an authorization for taking off or landing at a specific airport during a given time period: “Air traffic controllers have limited slots at busy airports.” Also known as a flight slot.

A slot is a dynamic placeholder that either waits for content (passive slot) or calls out to it (active slot). A scenario may specify that it should fill its contents, or a renderer might specify the presentation of the content.

Modern slot machines use microprocessors to assign different probabilities to each symbol on a reel, and then display those symbols in combinations on the screen. Symbols vary from classic fruits and bells to stylized lucky sevens, and many slot games have themes. Some have multiple paylines, and others have special symbols that trigger bonus levels or other features.

In the context of a computer, a slot is a place to store an expansion card. There are a variety of slots available on motherboards, including ISA slots, PCI slots, and AGP slots. A slot can be occupied by a single card or by multiple cards in parallel. If multiple cards are in the same slot, they are said to be in a bus-multiplexing configuration. A bus-multiplexing configuration can be faster than a standard single-card slot. For this reason, some people prefer to use AGP slots rather than ISA or PCI slots.