A slot machine is a casino gambling machine with three or more reels which spin when a button is pushed. Slot machines are also known as one-armed bandits because they were originally operated by one lever on the side of the machine as distinct from a button on the front panel and because of their ability to leave the player impoverished or in debt and because bandit can be a synonym for "thief" in modern usage. Many modern machines are still equipped with a legacy lever in addition to the button. Slot machines include a currency detector that validates the ticket inserted to play. The machine pays off according to patterns of symbols visible on the front of the machine when it stops. Modern computer technology has resulted in variations on the slot machine concept. Slot machines are the most popular gambling method casino in the world. A person playing a slot machine can insert coin or ticket-in, ticket-out machines, a paper ticket with a barcode, into a designated slot on the machine. The machine is then activated by means of a lever or button, or on newer machines, by pressing a touchscreen on its face. The game itself may or may not involve skill on the player's part or it may create the illusion of involving skill while only being a game of chance. The game usually involves matching symbols, either on mechanical reels that spin and stop to reveal one or several symbols, or on simulated reels shown on a video screen. The symbols are usually brightly colored and easily recognizable, such as images of fruits, numerals or letters, and simple shapes such as bells, diamonds, or hearts; newer video slot machines use animated cartoon characters and images of popular actors or singers. Most games have a variety of winning combination of symbols, often posted on the face of the machine (or available on a different screen, accessible by touching a button on the main touchscreen, on video slot machines). If a player matches a combination according to the rules of the game, the slot machine credits the player credit's or some other sort of value, such as free spins or extra games.