In gambling, a slot is the space into which coins are inserted or cards and bets are placed. It is also the name of a casino game and can be found online, with many offering free demo versions for players to try before they make their real money deposit.
A slot is also the time when a radio or television programme is broadcast, although this meaning is less common in British English. A slot in the sense of a machine or other mechanism is also used for security purposes, for example an electromechanical machine would have tilt switches that made or broke a circuit when it was being tampered with. This was to stop the machines from paying out without being authorised to do so, and was known as “tasting” the machine.
Modern electronic slot machines have more than 22 reels, each with several hundred symbols. To prevent a machine from cheating, manufacturers weight the probability of each symbol appearing on the payline in relation to their frequency on the physical reel. This gives the appearance of a hot or cold machine, although the underlying probability is unchanged.
Air traffic management slots are allocated to airlines for flights at congested airports, allowing them to save time and fuel by staying on the ground rather than in the air waiting to land. These are managed by EUROCONTROL, and since they started being used twenty years ago, there have been major savings in delays and fuel consumption.