A narrow opening in something, such as a door or the mouth of a barrel. Also: a groove, track, or trail that is followed by a deer or other animal.

A gambling machine in which coins or tokens are inserted and pulled or pushed by a handle to activate one or more reels marked into horizontal segments by varying symbols. When the symbols line up, the machine pays off by dropping into a cup or trough from two to all the coins in the machine. Symbols traditionally used include stars, card suits (hearts, diamonds, and clubs), bars, numbers (7 is a favorite), various pictured fruits (cherries, oranges, lemons, watermelons, and plums), and the words jackpot and bar. In 1909, to circumvent laws against gambling, the Industry Novelty Company replaced suitmarks on their machines’ reels with pictures of fruit to make them look like chewing gum dispensers and called them slot machines; this strategy failed, but the jangle of the coins in the cup or trough is still a draw for many gamblers.

This article covers only traditional slots; new skill-based slots are covered in a separate article. There is a companion page on par sheets. There are a lot of different reasons why people play slots, but the main ones seem to be the arousal they provide and the hope that they will hit the jackpot. Research suggests that long-term experience with slot machines tends to be disappointing, but players are often able to justify the price they pay for this disappointment by believing that they are buying excitement, not just money.