A slot is a dynamic placeholder that either waits for content (a passive slot) or is called by a renderer to provide that content (an active slot). The contents of the slot can be either a repository item or an object with a set of attributes.
The slots of a slot machine are rotating reels with symbols that pay out credits based on a preset paytable. A player can insert cash or, in “ticket-in, ticket-out” machines, a paper ticket with a barcode and activate the machine by pressing a lever or button (physical or on a touchscreen). The reels spin and symbols land randomly on a payline; winning combinations earn credits according to the paytable. Many slot games have a theme, and the symbols and bonus features are aligned with that theme.
Modern electronic slot machines are programmed to weigh particular symbols, which can increase the odds of them appearing on a winning combination. The weightings are usually based on the relative frequency of each symbol in the overall population of symbols on the reels, but can also be based on their color or shape.
A malfunction that makes a machine unplayable is referred to as a “tilt.” This term stems from electromechanical slot machines’ tilt switches, which would make or break a circuit if the machine was tilted or otherwise tampered with. Though most modern slot machines do not have tilt switches, any sort of technical fault is still a “tilt” to players.