Older mechanical slots work with physical reels and a coin mechanism: a coin drops past sensors that check its size and weight, a lever or button releases the reels, and stops on each reel decide the symbols. Class II slots, found in some venues, work differently again: each spin is really a round of bingo against other players, and the reels simply display the outcome of that draw in a familiar form.
Paylines on a slot machine are the patterns across the reels that count as a win, from a single middle line on classic games to hundreds on modern ones. Megaways games change the number of symbols on each reel every spin, giving tens of thousands of ways to win. The buttons set the stake and the number of lines. Which type of slot machine is best depends on what a player wants: steady small wins, or rare large ones.
A few questions come up about what happens behind the scenes. When a slot machine is reset after a jackpot or a fault, nothing about its odds changes; the generator keeps running. When a machine malfunctions, the rule printed on most games voids pays and plays, and the logged result settles any dispute. Slot machines cannot be adjusted on the floor without approval and new software. Hacked machines are a rare crime, not a player strategy, and old slot machines are usually scrapped or sold to collectors.