Slot machines use a number of different symbols to determine the outcome of a spin. Many machines also have a paytable that lists the number of credits that a player can win when a specific combination of symbols lines up on a payline. The paytables are typically found on the machine face, above or below the spinning reels. Alternatively, they may be found in the help menu.

In the United States, slot machine availability is heavily regulated by state governments. Some states have even established their own gaming control boards, which are charged with overseeing the industry. The evolution of slots has spanned many decades. The first fully electromechanical slot machine was produced by Bally in 1963. But the basic electromechanical construction had already been visible in earlier models, including the High Hand draw-poker machine of the 1940s. The Money Honey machine was another popular machine with a bottomless hopper that automatically paid out up to 500 coins. This machine’s popularity spurred a trend toward more electronic games and eventually replaced the side lever.

While Nevada has no significant restrictions on private ownership of slot machines, New Jersey, Louisiana, and Missouri only allow casino-style gambling on riverboats. After Hurricane Katrina, Mississippi eliminated this restriction for Gulf Coast casinos. In Delaware, slot machines are allowed at three racetracks but are regulated by a state lottery commission. In Wisconsin, up to five machines can be found in bars.