A narrow depression, perforation, or opening, especially one for receiving something, as a coin or a letter. Also, a period of time in a schedule or sequence: He booked his haircut for the 2 pm slot.
The first recorded use of the word was in the 19th century, when a New York-based company called Sittman and Pitt invented a machine that allowed players to win by lining up poker hands on its reels. But Charles Fey improved on their invention in 1887 with a version that used three instead of five reels, made payouts automatic, and replaced the poker symbols with diamonds, hearts, spades, horseshoes, and stylized liberty bells (the latter were the highest winners).
More recently, the term has come to refer to any type of slot machine—an electronic device that accepts cash or paper tickets with barcodes and activates rotating reels that display varying combinations of symbols. Some slots offer multiple paylines, while others have bonus features like progressive jackpots and free spins.
In the context of online casino games, a slot is a dynamic placeholder that either waits for content (a passive slot) or calls out to get it (an active slot). Slots work in tandem with scenarios and renderers. For example, a renderer could fill the content for a slot that has been configured to allow media-image items or video to be placed in it. However, it is generally not recommended to feed a slot with more than one scenario.