A slot machine is a casino game in which players place bets by inserting coins, paper tickets with bar codes, or other payment methods. The slot machine then spins the reels and awards credits based on the paytable. The symbols on the reels vary according to theme, but the classic symbols include fruit, bells, and stylized lucky sevens. Most slot machines feature bonus features, which are usually related to the theme.

In the mid-twentieth century, the video slot came into popular use. Video slots work the same way as traditional slot machines, but instead of spinning reels, they feature a video image instead. When video slots were first introduced, players were hesitant to play them because they lacked the traditional appeal of spinning reels. However, manufacturers now incorporate reels and handles into video slots to create the illusion that players are in control of the outcome.

While some states restrict the use of slot machines, most do not have significant restrictions. Specifically, Nevada and New Jersey allow the use of slot machines in bars, but restrict the operation of gambling establishments on riverboats and in small shops. Mississippi removed the barge requirement for casino-style gambling along the Gulf Coast after Hurricane Katrina. Other states allow slot machines in specially-authorized gambling zones, but there are some exceptions.

Most machines with multiple pay lines offer players the ability to select how many lines to play. While the minimum bet is only one line across the reels, the possibility of playing extra horizontal and diagonal lines is also available. This way, players can win more coins. However, players must keep in mind that the maximum payout is usually only possible when a player wagers the maximum bet.