A narrow opening, as in a door or window. Also: a position in a sequence or series (such as an open time slot on a calendar). The gap between the face-off circles of an ice hockey rink. In computing, a place for an expansion card in a computer motherboard.

A slot is a dynamic placeholder that waits for or calls out for content dictated by either an Add Items to Slot action or a targeter. The content is then displayed by a renderer, which specifies how it should be presented on the page. A slot is closely related to a scenario, which is used to manage content in a template.

The earliest slots were mechanical devices that paid out credits when a lever or button was pushed. The first machine was invented in 1895 by Charles Fey and featured three spinning reels that lined up symbols to make poker hands when a lever was pulled. Later designs included symbols such as hearts, spades, horseshoes, and the eponymous liberty bell.

Modern variations of slot machines have become vibrant, feature-packed games that offer a variety of ways to win. Some of them feature multiple paylines and expanding reels to expand the opportunities for winning combinations. Others offer themed graphics and bonuses tied to popular culture or classic themes.

To play a slot game, a person inserts cash or, in “ticket-in, ticket-out” machines, a paper ticket with a barcode into a designated slot on the machine. A computer then selects a set of stops on the reels and a random number is generated to determine how much the player has won.