A slot is a narrow opening or groove in something. You can put letters and postcards through a mail slot at the post office. A slot on a computer or other electronic device is an opening into which data can be entered and retrieved. A slot on a video game is an area of the screen that is reserved for displaying symbols, and a player can place bets in multiple slots.
In a slot machine, players insert cash or, in “ticket-in, ticket-out” machines, a paper ticket with a barcode and activate a lever or button to spin reels that rearrange symbols. When a winning combination of symbols appears, the machine pays out credits according to its paytable. A variety of bonus features may also be available. Each machine has a theme, and the symbols used in the game reflect this theme.
Modern slot machines use electronics to determine winning combinations. Historically, slot machines used revolving mechanical reels to display and determine results. These reels typically had only three physical symbols and allowed a maximum of 103 = 1,000 combinations. Consequently, jackpot sizes were limited. Eventually, manufacturers added more physical reels to their machines and electronically weighted particular symbols. This made it more difficult to win the jackpot.
In addition to the timing of wins and losses, slot machines provide players with substantial auditory and visual feedback when they make a profit (Griffiths & Parke, 2005). In fact, large profits are often accompanied by high-fidelity attention-grabbing music and amusing animations that are designed to keep gamblers playing. This feedback is an important component of slot machine enjoyment.