A slot is a narrow opening in something that allows it to be inserted. In the case of a machine, a slot is where coins are placed in order to activate the machine. It may also refer to a time period in which an activity takes place. For example, a visitor to an office could book a specific time slot to meet with a staff member in order to discuss an important project deadline. Using slot to schedule important objectives can help support productivity and workflow.
In the context of air traffic control, a slot is an authorization for a planned aircraft operation at a congested airport during a given time period. Slots are used to reduce the number of aircraft trying to take off or land at busy times, thus avoiding the long delays and fuel burn that result from too many flights at once.
A slot is also a position in the reels of a slot machine that contains symbols that can win you credits when they line up on a winning pay line. The symbols can be wild and represent multiple other symbols or they can be a multiplier symbol, like a 2X wild symbol that doubles your wins on the pay lines when it appears. The odds of a winning symbol are determined by a random number generator that cycles thousands of numbers each second, and the results are then displayed on the reels. The microprocessors in modern slot machines allow manufacturers to assign a different probability to each symbol on each reel, which makes it seem that a certain symbol is close to lining up with a pay line.