A narrow notch, groove or opening as in a keyway in machinery or a slit for a coin in a vending machine. Also: a position in a group, series or sequence; an allotment of time to perform a task.

You’ve checked in, passed security, found your gate, queued to get on board and struggled with the overhead lockers. Then you hear the captain: “We’re waiting for a slot.” What is a slot and why can’t we take off as soon as we are ready?

A slot is a period of time allocated to an airline or other passenger service. Airlines use slots to ensure that they can operate when airports are constrained by runway throughput, congestion or other factors.

In a slot game, a player inserts cash or, in “ticket-in, ticket-out” machines, a paper ticket with a barcode into a designated slot on the machine. The machine then activates the reels and stops them when a winning combination of symbols line up on the pay line, earning credits based on the game’s pay table. Symbols vary from machine to machine, but classic symbols include fruits, bells and stylized lucky sevens.

Unlike traditional fruit machines, which can be programmed to give out more wins than others, slots are kept fair and unpredictable thanks to the Random Number Generator (RNG). An RNG creates new combinations of patterns and numbers every second, so the outcome of a spin is decided the very moment you press the button.