When most people think of slot machines, they envision classic mechanical designs with spinning reels and flashing lights. While these machines still exist and continue to be a casino favorite, most modern versions operate on a completely different principle. They use computers to determine the outcome of each spin. So if you pull the handle and nothing happens, don’t worry: It just means that computer was busy making thousands of calculations per second.

One of the best things about slots is that they’re simple. You just put in your money, and then you watch the results. Generally, you win by getting matching symbols in a row along the pay line (a path across the reels) when you activate the machine. The number of symbols and the payouts vary by machine, so you should always check out a machine’s paytable before playing.

Another good thing about slots is that they’re based on random numbers. Every time a machine is activated, the random-number generator generates a series of numbers and assigns them to the positions of the symbols on the reels. When the machine receives a signal — anything from a button being pressed to the handle being pulled — the random-number generator selects a combination and the reels stop on that combination.

This process is a crucial part of the fun and is also why casinos can afford to pay out winnings — because they make a profit from the difference between the amount that is put into the machine and the amount that is paid out. To get the most out of your slot experience, it is helpful to plan ahead and play with a budget.