A slot machine (also known as a fruit machine, puggy, or simply slot) is a casino game where players bet on spinning reels to try and match symbols, earning credits based on the paytable. The game usually features a random number generator to produce results.
Traditionally, slot machines used revolving mechanical reels to determine payouts, but modern microprocessor-based games offer a much higher level of automation. The chance of matching a winning combination of symbols is calculated using the probability of a particular symbol appearing on each reel.
If a player wins, the machine displays the amount of money won and pays out the remaining credits. The machine may also have a bonus round or free spins feature, which can result in additional payouts.
In most casinos, slot games are the primary source of profits, so gaming managers make it their business to keep customers playing and spending as long as possible. They typically lower the house edge to increase slot play, which increases their profit over time.