Slots are known by different names across the globe, from “fruit machines” in the UK to “pokies” in Australia. But no matter what they’re called, these games remain the leading revenue generators for almost all land-based and online casinos. In this article, we’ll look at how a modern slot works, the leading manufacturers of games, and the always-elusive payback percentage.

How a Slot Machine Works

There’s one primary element to modern slot machines: the random number generator. As soon as a slot becomes active, this function starts generating random numbers at an inhuman rate (usually hundreds per second).

The instant a player presses the spin button on a slot machine, the random number generator (or “RNG”) grabs the most current series of digits and uses them to determine the outcome. While the spinning symbols present the illusion that the final result is determined one reel at a time, it’s actually over as soon as the player decides to press the button. Of course, slots would lose much of their appeal if the results were instantly displayed.

Even though winning symbols are selected at random, some are programmed to appear more often than others. If this weren’t the case, wild and bonus symbols would turn up at a much higher frequency and result in a major loss for the house.

Despite superstitions to the contrary, slot machines are not programmed to run hot and cold. A game might go 20 years without paying out a progressive jackpot, or it might deliver two of them in the same day. That’s good news for the customer, as it means playing right behind a jackpot winner gives you the same odds of success as they had.

Payback Percentage

While the result of each spin is random, slots are also programmed to pay out a certain amount over the long run. This is known as the payback percentage, and it represents the payout over an infinite number of spins.

While most casino games openly advertise their odds of winning, this is not the case with slots. The payback percentage is guarded by casinos, and much of this is due to the fact that some machines pay out more than others. If customers were aware of the difference, they would flock to select games and abandon the others.

The house edge on most slots ranges from 6% to 15%. Land-based slots have to pay out a minimum amount as determined by their state or country, while online games tend to be less regulated. If you stick with a reputable Internet casino that uses software from a leading provider, however, you should be okay.

Leading Slot Machine Makers

If you’ve ever played a slot machine, there’s a strong chance that one of the companies listed below was responsible for making it.

WMS Gaming

Under the Williams brand, this company has long been a leader in the gaming business. Fans of multi-line, secondary bonus payouts should be interested to know that WMS was the first to offer such features. They’re best known, however, for their wide range of licensed properties, including the following: Flintstone, Mad Men, Wizard of Oz, Monopoly, The Price is Right, Gone with the Wind, Lords of the Rings, and The Godfather.

Realtime Gaming

Founded in 1998 and including clients such as Bodog, this online casino company is known for their progressive slots, many of which are connected across all casinos powered by RTG.

Aristocrat Leisure

The largest game manufacturer in Australia, as well as one of the largest slot machine makers in the world. Aristocrat built their first slot in 1953, and they’ve since grown to become a publicly traded company. Some of their notable licensed games include Superman, Batman, The Walking Dead, and the Rolling Stones.


Listed on the New York Stock Exchange, this company is responsible for making half the slot machines in the United States each year. Active in both the online and land-based arena, they’re responsible for titles such as Sex and the City, Star Wars, Let’s Make a Deal, and Jeopardy.


Responsible for one of the largest online payouts in Internet history, this virtual gaming manufacturer provides software for 32Red, Ladbrokes, and numerous others.


Based in Nevada and founded in 1968, this company was once famous for their pinball machines and video games. Now they make slots for traditional and virtual casinos, with some of their leading brands consisting of Grease: Pink Ladies, Pawn Stars, Vegas Hits, and ZZ Top: Live from Texas.

Due to their colorful graphics and the allure of a quick payout, slots should remain the top draw for casinos for decades to come. While the information listed above won’t increase your payback percentage, it should at least make you feel more like a veteran gambler while you’re pressing the spin button.