A narrow notch, groove or opening, as in a door handle, mail slot in a letterbox or a coin hopper in a vending machine. Also a position in a group, series, sequence, etc.
A slot is a dynamic placeholder that either waits for content (passive) or calls out to a renderer to fill it with content (active). It is possible to use multiple scenarios to feed a single slot, but it is not recommended. Each slot can hold only one type of content.
It is common for people to assume that a machine that has gone long without paying out is due to hit soon. However, chasing a machine that is supposedly due to payout will only result in a longer losing streak. It is far better to pick a machine that has recently paid out and try again.
Airport slots
An airport slot is a time reservation for an airline to fly at a congested time. The use of central flow management slots by EUROCONTROL has led to major cost savings in terms of flight delays and fuel burn, and it is now being rolled out to other parts of the world. This is a major achievement given the fact that there are often very tight constraints on the airspace available for flights in many parts of the world. These constraints can be caused by runway congestion, weather conditions or parking space.