A slot is a position within a group, series, or sequence of events.

A game of chance in which symbols appear on a series of spinning reels, with the aim of matching them along pay lines to win. The number of possible combinations is limited by the number of symbols on each reel, and the probability that a particular symbol will appear on a given pay line is determined by a random number generator. Modern electronic slot machines often display a sequence of probabilities for each reel as well as the total amount that may be won.

Casino operators often worry that increasing the house advantage too much will drive away customers, especially if players can detect hidden increases in prices simply by playing the slots (Blaszczynski, Sharpe, Walker, Shannon, and Coughlan, 2005). In addition to the psychological reasons why people play slots, many people have serious gambling problems that can lead to severe debt, family, work, and social difficulties.

A slot is also a term used in the aviation industry, specifically for airplanes, to describe a time period of authorization for a plane to take off or land at a busy airport. Air traffic control uses slots to manage air travel at high-traffic airports and prevent repeated delays from too many flights trying to take off or land at the same time. This is a critical function to provide safe and efficient airline operations, and is also a key component of air quality management programs at airports.