A slot (plural: slots) is a narrow depression, perforation or other aperture; especially one for receiving or fitting a piece that slides in it. A slot can also refer to a time period within a schedule or sequence, such as the 2 pm slot for haircuts.

In a video slot game, the reels are arranged in rows and columns with a number of paylines visible on each. To win a game, players need to line up three or more matching symbols on an active payline. Some video slots offer multiple paylines, while others have a fixed number that are always in play.

Some slot games include bonus features that increase the chances of winning. For example, a game might feature wild symbols that act as substitutes for other symbols and can expand to fill an entire row on the reels. These can trigger other special game features, such as free spins or a jackpot level. Alternatively, a game may have fully themed and interactive bonus rounds that can lead to big prizes.

The first slot machines were created in the 19th century by Sittman and Pitt, who devised a machine with five reels that displayed a total of 50 playing cards. Winning was possible by lining up poker hands. Charles Fey improved on this concept, replacing the cards with symbols such as diamonds, spades, horseshoes and hearts. His version became known as the Liberty Bell and was very popular. Today, slot machines can be found in many casinos and other gambling establishments.