A narrow notch, groove or opening, as in a keyway in machinery, a slit for a coin in a vending machine, etc. A position in a group, series, sequence, or hierarchy. Also, a piece of equipment in a slot, such as a landing gear or a throttle.
A slot is a dynamic placeholder that either waits for content (passive slot) or calls out for it (active slot). A slot can reference a repository item directly using the Add Items to Slot action or a targeter to fill the slot with content.
Slots can also refer to positions in a queue for air travel or space on a train, boat or other vessel. The use of slots as part of central flow management has resulted in huge savings in terms of flight delays and fuel burn for the airlines. It is important to remember, however, that the time savings achieved by avoiding queues at airports and other transportation hubs may not be realized when you are sitting in the air waiting for a slot to open up in the sky!