A slot is a dynamic placeholder that waits for (passive) or calls out for (active) content. Slots are defined and managed using the ACC; like renderers, they can either reference a repository item directly or point to a targeter that fills the slot with content.

Charles Fey is credited with the first successful slot machine. His invention incorporated several improvements over the Sittman and Pitt design, such as automated payouts. Fey’s machines used different symbols, including spades, hearts, horseshoes, diamonds, and liberty bells, in addition to traditional poker chips. He also added a “maximum win” feature that paid out if three aligned liberty bells appeared on the pay line.

Modern slot machines use microprocessors to assign different probabilities to each symbol on each reel. This gives the impression that certain symbols appear more frequently on the reels than others, although in reality all the symbols have equal chance of appearing. This allows for a larger number of possible combinations and increased jackpot sizes.

The most popular type of slot is the Egyptian-themed game Cleopatra. This IGT creation has ancient Egyptian music, pyramids, scarabs, the Eye of Horus, and the Queen herself as symbols, with a variety of bonus features and free spins. The game’s popularity has resulted in a sequel, Cleopatra II, with more Egypt-themed symbols and even bigger bonuses. Many online casinos offer a wide range of slots, with various themes and payouts. Some offer progressive jackpots, while others have fixed prize levels that increase the longer the slot is played.