Traditionally, the term ‘slot machine’ was used to describe a gambling machine that was operated by inserting coins, or tokens, into a slot and pulling a handle, or pressing a button, to set in motion three or more, originally mechanical, reels. The final position of the reels or, in other words, how many winning symbols lined up on the payline, or paylines, determined the payout, which was released, again in coins, or tokens, into a receptacle at the bottom of the machine.
The principle of the modern slot machine remains the same but, in casinos in the United States and elsewhere, coins and tokens have been almost universally replaced by a system known as ‘Ticket-In/Ticket Out’, or TITO for short. TITO slot machines neither accept nor pay out in coins or tokens, but instead print barcoded tickets that can be transferred from one machine to another, or redeemed for cash at a cashier station or automated kiosk.
Similarly, in the modern incarnation of the slot machine, physical, mechanical reels have been with a graphical simulation on a video screen, which simply display the outcome of each spin, as determined by a microprocessor, known as a random number generator. In addition, while traditional slot machines had just a single payline, modern slot machines with two, three, five or more paylines have become commonplace. Nevertheless, for all their ‘bells and whistles’, in terms of complexity and features, modern slot machines typically offer a house edge between 5% and 10%.