Slot machines are games in which you pay by inserting coins or paper tickets with barcodes. Once the machine has been activated, it spins the reels until a winning combination is formed. This winning combination then earns the player credits, depending on the paytable. The symbols on the slots vary, but many classic games feature bells, fruits, or stylized lucky sevens. The themes of slot games are also important, as they will often be associated with the bonus features.

The machine also has a computer that controls step motors to turn the reels. The computer drives these motors by sending short digital pulses of electricity. These pulses move the motor a certain increment each time, ensuring the accuracy of the process. The computer is not pre-programmed to pay out the winning combination, and it uses a random number generator to ensure that each spin has an equal chance of being won.

When slot machines first became popular, they were often installed in casinos as a diversion for casual gamers. Since you do not need to be a professional gambler to play them, anyone can easily play them with a small bet. Over time, they became the most popular game in town, bringing in 60 percent of the gaming revenue in the United States.

As technology has improved, game makers have added new features to slot machines. Some new versions of slot machines are built around particular themes. For example, there are slots based on television shows, sports, poker, and even horse racing.