A slit or other narrow opening, especially one for receiving something, such as a coin or letter. (Micro-)A slot is also a position in a team or game, either on a field or in the case of an ice hockey rink, between face-off circles.

A slot is also the name of a container for dynamic items on a Web page. Slots are defined and managed using the slot> element, which is part of the Web Components technology suite. A slot can either wait for content (a passive slot) or call out to a renderer to get the content to fill it (an active slot).

In the late twentieth century, slot innovation continued as manufacturers incorporated electronics into their machines. These systems allowed them to weight particular symbols so that a single symbol appeared on multiple reels more often than it would in real life, increasing the likelihood of a winning combination and boosting jackpot sizes. Manufacturers also programmed them to display windows showing the accumulation of coins, which has proved an effective lure for many players.

Psychologists have warned that video slot machines can trigger gambling addictions in people who have not previously experienced them. The 2011 60 Minutes report “Slot Machines: The Big Gamble” highlighted the risks. Research has shown that players of video slot machines reach a debilitating level of involvement with gambling three times more rapidly than people who play traditional casino games. They are often influenced by their emotions, including fear and anger, as well as by their perceptions of the odds.