Slots Guide

This page is designed to connect you to reliable information about slot machines. Our goal was to produce a guide to slots that covers every related topic from one easy-to-search location. Far more than a standard slot review site, we hope to provide perspective on the entirety of the slot industry.

Our guide to slots offers detailed reviews of popular online and land-based slot machines. We also cover the free-play slot market for fans of recreational machine gambling. Since the Web-based slot gambling industry is so different from the traditional casino slot scene, we cover online slots as a distinct category. Our notes on game strategy include the debunking of slot myths, notes on proper bankroll management, and a common-sense method to help you pick the right game.

If you have a question about slots, interest in a particular slot game, or a general curiosity about slot machines, you'll find the information you need somewhere in our coverage of the world's favorite way to gamble.

There's more to our comprehensive guide to slot machines than reviews and basic information. Below, you'll find detailed lists of slot designers, strategy articles, a game FAQ, and a thorough glossary of slot terms every player should know.

Introduction to Slot Machines

We know of very few gambling rules that you can apply across the board.

One of them is "Never take insurance against a dealer blackjack."

Another rule of thumb that we support 100% says the Tie bet in baccarat is for suckers.

Still another gaming idiom holds that the easier a game is to understand, the worse the odds are. We've found that this is the case when it comes to slot machines.

We put this page together as a compendium of everything we know about slots. We cover slot machine origins and the development of the games into modern slots, discuss modern takes on slot strategy, provide details about different game styles, and fill in the rest with whatever else a person might want to know about the one-armed bandit.

Slots are appealing because of their simplicity, their visual and audio effects, and the huge jackpots seemingly available for the drop of a coin or a credit. Since playing slots is literally as easy as pushing a button, it should come as no surprise that the games give the casino a big advantage. Throw in the quick rate of play germane to slot machines, and you've got yourself a very profitable machine.

Let's look at how slots took over the American gambling landscape.

What is a Slot Machine

You'd know a slot machine if you saw it, right?

Slot machines have big flashing lights at the top. They make a lot of noise. They have a certain shape of case covered in boldly-painted letters, symbols, and numbers. They use spinning reels. They're big, noisy, mechanical things that promise big riches for small wagers.

You're right, of course. That does sound like a slot machine. But technology has brought these games a long way from the one-armed bandits of the American frontier.

To understand what a slot machine is, we should start with a generic definition.

Traditionally, slot machines were coin-operated, and the player pulled a lever to activate three spinning reels, with coins dropping out into a hopper after wins. That's changed over time. Now, the phrase slot machine includes games that don't use a lever or accept coins at all. Forget the old-school hopper – these days, prizes are generated electronically, like the wagers themselves.

The Shorter OED defines the phrase in a scientific way that we appreciate – "a gaming machine that generates random combinations of symbols, with certain combinations winning varying amounts of money for the operator." By this definition, video poker games are slot machines. They involve an added skill element, and the winning combinations are a bit more familiar to us, but technically, you could call it a slot and no one would argue with you.

Is it a mistake that the video poker machines look and behave much like slot machines and are kept in the same part of the casino? The gaming floors of Las Vegas are increasingly home to skill-based games that are also based on slot machine design, but offer a totally different skill-based element. More and more, these games are hosted right there next to the classic slot and video poker machines.

The History of Slot Machines

The history of slot machines begins with the invention of coin-operated mechanical devices around the year 1880. At that time, America was expanding rapidly to the West. Frontier towns not unlike the dusty hardscrabble villages you find in classic Western films were popping up as Manifest Destiny asserted itself.

The invention of coin-op devices was kind of inevitable. The people of the frontier were nothing if not crafty. They also found themselves with an ever-increasing amount of leisure time. At the same time, they had new access to inexpensive metal goods. Knowledge was spreading, as was the entrepreneurial spirit and the patent market.

In the beginning, these gadgets were novelty items. Found mainly in bars and restaurants, they were more like games than anything else. A popular game at the time featured a "race" between two toy horses, triggered by inserting a coin in the machine. Bettors would gamble on the outcome among themselves, rather than using the machine itself.

By the year 1888, machines that paid out real coins were patented, though they weren't that popular. These were crude devices and required a lot of upkeep. They were also notoriously easy to rip off. More popular were games that paid off in prizes from the bartender – coins, free drinks, cigars, etc. An example of these early games would be a simple three-card poker game. Your prize varied depending on which cards sprang up. The bartender would then reward you accordingly.

A Bavarian-born American citizen, an inventor by the name of Charles August Fey, is responsible for the first game that we can call a true slot machine. Fey was working as a mechanic in San Francisco, a town in the middle of a boom thanks to the discovery of precious metals and the expansion of the American West. Bored with his work, he built the first known coin-operated slot machine in 1894. He failed to interest a single shopkeeper, but kept working on his invention in his own time. His game was called The Card Bell.

By 1896, his Card Bell game was revamped as a three-reel slot machine with an auto cash payout mechanism. It proved to be so popular that Fey was forced to quit his job, open a factory, and produce units as quickly as possible. The game itself would be recognizable to modern gamblers – it featured a level that set three spinning reels in motion. The symbols were based on the traditional playing card suits, which lined up to (hopefully) form a valuable poker hand.

But Fey had a problem. This was frontier America, a country still very much under the influence of Puritanism. Ministers railed against the evils of gambling with cards. In many of the towns Fey visited to try to expand his gaming empire, he ran up against townspeople predisposed to distrust card playing.

Fey wouldn't make the same mistake with his next slot. Called the Liberty Bell, it contained absolutely no references to cards or other common forms of gambling. The first Liberty Bell was completed in 1899, featuring symbols like horseshoes, bells, and numbers. Though some playing card symbols were incorporated, the focus of the game was on the lining up of three giant bells, and patriotic ones at that.

Having safely sterilized his machines, he could now get them put up in saloons, shops, restaurants, and public spaces all over the country, even in markets where gambling with cards was frowned-upon.

The use of fruit symbols in slot machines is a tradition going back all the way to 1909.

That year, the Industry Novelty Company started mass-producing machines in the style of Fey's old Liberty Bell. Like everything else about the slot machine, fruit symbols were a necessity. The use of symbols in the shape of cherries, bananas, and grapes was an attempt on the part of Industry Novelty to disguise the gambling aspect of their game. Where Charles Fey incorporated horseshoe and bell symbols to cover up the game's similarity to illegal card games, Industry Novelty turned to a pack of chewing gum.

Industry Novelty's earliest slot machines were manufactured as "chewing gum dispensers." Each of the game's reel symbols indicated a particular flavor of chewing gum. The idea was that if you won, the game would dispense the flavor that correlated to the symbols you lined up. To make the subterfuge really stick, some games were produced that actually did reward players with chewing gum. Of course, the vast majority were altered after-market to pay out coins.

The early 20th century was a time of much upheaval and change on the domestic front. Unfortunately for slot lovers and gamblers, the country's general suspicion of gambling turned into full-bore gambling prohibition, so that by the year 1951, virtually all gambling in America was illegal. That changed in the 1930s, when the city of Las Vegas officially re-legalized gambling.

It's fair to say that Vegas saved the slot machine, and (eventually) elevated it to the level of great art. The development of electro-mechanical slots in the 1950s gave slot designers the freedom to innovate, and innovate they did. New payout schemes, jackpot styles, graphic and audio effects, and features like coin multipliers were all added in the decade of the 1950s. Two decades later, Vegas was home to the world's first video slot machines, games using simulated reels on a display rather than mechanical reels in a case.

At first, these new games were unpopular. Slot players were used to pulling a physical handle to initiate actual spinning reels. They wanted the classic sights and sounds, regardless of what great new technology was under the hood. Video slots were kind of a bomb at the time of their release.

Not only did game designers get better at producing titles that would appeal to slots players, but they figured out a way to link slot machines at different casinos to create a massive progressive jackpot. These jackpots were a great advertising tool, soon handing out top prizes that far surpassed the old Vegas Strip jackpot records.

The creation of linked slot networks came just at the right time. In the 1980s, a new gambling audience was emerging. Younger, wealthier, and more image-conscious than the gamblers Vegas had grown accustomed to, these new gamblers often valued flash and style over tradition and substance. As video slot technology improved, and jackpots set new records on a weekly basis, slot machines became hip in a way that roulette and baccarat never could. Slot machines were already easy to play, inexpensive, and potentially very lucrative – the addition of video effects and progressive prizes made them the state-of-the-art in gaming technology.

Introduction to Slot Machines

Because so many different styles of slot machine exist in the modern world, it's difficult to answer this question just once. We'll offer three answers, looking in brief at the way that classic, modern, and online slots operate.

These games are sometimes called mechanical slots, for good reason. Old-school slot machine games work like a clock, with actions based on the movement of a specific configuration of levers, gears, and buttons.

If you were to open up a classic slot machine and look at its guts, you'd see one main central metal shaft supporting the game's reels. This is the heart of the machine. This shaft is connected to the lever other handle mechanism that initiates a round of play.

The machine also needs a way to bring those spinning reels to one of a series of specific stopping points, so you'll notice a braking system of some sort. In modern times, these braking systems got kind of high-tech, since these were the parts of the machine most likely to break and cost the operator time and money.

If you dig deep enough, you'll also find a series of sensors that indicate where the reels have stopped, and initiate the payout system. The whole thing is kicked off by another sensor at the "coin-in" position that indicates if the proper amount of money has been inserted, and unlocks the game's braking system so the handle and reels can move.

Early versions of mechanical slot machines didn't have the kinds of sensors you're probably thinking about – they used mechanical devices to "read" the coin and dispense the proper amount of coins into the hopper.

What about those spinning reels? Attached to that main shaft we described above are three special discs. These discs have notches in special places that match up with the kicker paddles. These discs connect to the three reels, and are the engine of the game's final decision. Those kicker paddles exist on a second shaft below the main shaft, each of which supports a paddle-shaped piece of metal. Attached to that additional shaft – a series of stoppers and "teeth" that fit perfectly into the notched discs described above.

These classic games were basically powered by spring tension. The kicker paddles and all the stoppers were spring-loaded, and were held even in standby position under spring tension. The machine's stoppers were held tightly against the discs, locked in place by the mechanism. When an operator pulls the handle or lever to initiate a round of play, the parts described above do most of the work, thanks to potential energy lent them by the springs.

The player doesn't see all that, of course. What the player sees is the spinning symbols, the lights on the machine's case, and the coins dropping into the hopper.

Obviously, this description doesn't necessarily apply to every classic slot machine ever made. Games with multiple reels and more complex clockworks were common by the end of the mechanical slots' heyday in the 1950s. With the basic elements described above, slot machines could take lots of forms, though their basic design was limited by the number of mechanical elements that would fit in the case. The elements described above can be arranged in a number of ways, and they can be adorned with all sorts of lights, noisemakers, and (eventually) basic graphic, audio, and video effects.

When we say "modern slots," we're talking about games you can walk into a casino today and find on the floor. Some casinos will have a few classic-style machines available, with just a few reels and simplified gameplay, but even those machines will run on a modern "brain." Here's the basics of how a modern slot game works.

Modern machines use a system of virtual reels, rather than real mechanical ones. Because each of these virtual reels can have an unlimited number of virtual symbols, modern games have multiple reels, pay lines, and other features that just weren't feasible with a mechanical design.

The spinning action of mechanical reels is what made those games random. This spinning function has been replaced by a gadget called a random number generator. Each virtual reel's stop position and the symbol associate with that position is determined by this random number generator at the time the player presses the "Spin" button. Because watching an algorithm pick random numbers would be kinda boring, the game's display shows an animation of spinning symbols, or some other audio-visual distraction. Designers and programmers can alter these virtual reels (and the random number generator itself) to adjust a machine's payout percentage and other features.

The addition of electronic and digital components to slots has created an amazing array of game styles. Slot games now feature things like complex plots, immersive audio and visual experiences, 3D graphics, licensed characters from films and TV shows, and plentiful bonus and side games and wagers to enhance the game's replay value. Modern slots are less like the clunky mechanical one-armed bandits of the frontier, and more like computer or console games.

The first online casinos opened for business in the late 90s. With Web-based betting nearing its second decade, gambling online is not exactly a new phenomenon. Online slots are easy to explain, in part because they're similar to traditional computer games, and in part because most people reading this page have probably tried their hand at a Web-based slot game or two.

If you understand the difference between mechanical and modern slot games – how modern slots depend on a random number generator rather than a series of gears and levers – then you already understand the basics of how online slots work. Since slot game outcomes can be produced without gears and levers, it makes sense that slots don't really need a physical presence at all.

Why do you need an actual screen and case, when you can easily replicate the whole experience with animation? Online slots are nothing more than modern slot games presented in a graphic interface and made available on the Internet. You can play these online slots for fun, or for real money wagers at online casinos.

Online slots can be designed to pay bonuses to players, just like earning reward points at a casino's slot club. Online games are often networked to produce progressive jackpots, just like slots on the casino floor. Web-based slots come in thousands of varieties, from classic-style three reel titles to more modern licensed games with skill elements and 3D graphics.

Types of Slots

Because these games have evolved so much in the century since their invention, we'd like to cover a few of the major categories of slot games. This list will be useful to people who are new to machine gambling, whether the goal is to play online or in a brick and mortar casino.

Free slot games are, by definition, any slot that doesn't require a real-money wager. These take many forms, from handheld video games to online trainer programs. The rise of mobile gaming has only increased the amount of attention developers are paying to the free-to-play market. Social media games involving gambling regularly include a variety of titles modeled after machine games, a testament to their widespread popularity.

Playing slots for free is good for little more than a distraction, though it's possible to "test out" games before you play them for real money bets at online and land-based casinos. Free slots are easy enough to find and play. Since no money moves between the player and the provider of the game, they aren't regulated in any way, and you can jump right in and play from your browser or download the game for convenient play without an Internet connection. Many free to play slot sites have 150 free games or more, all of which are accessible at the touch of a button.

The phrase "classic slots" has a couple of meanings. On the one hand, traditional slot games based on mechanical action are classic games. You'd be hard-pressed to find an actual classic mechanical slot in action on a casino floor, though we've seen a few in action mostly as novelty items. Collectors are likely to have traditional slots with mechanical parts, though it's illegal for these collectors to actually provide them as games of chance, so they're for display only.

The other meaning of the phrase refers to modern games styled after the classic machines of yesterday. Though these modern games still have electronic brains, they are configured with three reels and a single payline, or some similarly-small arrangement of reels and lines, in order to replicate the play style of traditional games. People enjoy these classic machines because of their simplicity, or because they're a throwback to a simpler time, before 3D graphics, licensed themes, and progressive jackpots.

The phrase video slots gets tossed around a lot online. We don't like the phrase, because it doesn't really describe a category of games. Really, any machine game that uses a modern display, or graphics, or animations, or cut away scenes can be called a video slot. To that end, we'd guess that 99% of all the slots online and in Las Vegas are technically "video slots."

An example would be Cleopatra slots, a popular line of online slot games based very loosely on the life and imagery associated with the historic Cleopatra. Produced by the online game design branch of IGT, these slots include video cutaway scenes, and all the other traditional trappings of online machine games.

The rise of video and audio effects on gaming machines was a natural step in the evolution of these games. As gamblers raised on computer and video game consoles started entering casinos, they demanded better graphics, more interesting plots, and better technology. The expansion of machine gambling into cyberspace has increased the pace at which these games are evolving new features. To try to describe a game as a "video slot" is pretty pointless. The only purpose for this phrase is to distinguish between classic slots and everything else. Still, we think it's important that you know the phrase if you're going to be playing slots in the modern age.

This phrase is really useful to people looking for a home for their online slot play. Any game that includes a round that rewards additional prizes, outside the scope of the spinning reels and symbols, is a bonus slot. But not all online slots offer these bonus rounds. Players who enjoy things like side wagers and skill games as part of their machine play hunt out "bonus slots," rather than a more generic phrase like "video slots." Bonus slots aren't just the domain of the online casino – land-based slots have included bonus rounds for decades before the advent of online gambling. These days, the majority of slots above the penny and nickel level include some kind of bonus round, whether it's a shooter-style skill game or the option to cut a virtual deck of cards for double your win.

Progressive slots are machine games that are linked across some sort of network. The purpose of this linking is to increase the size of the game's progressive jackpots. By shaving off a percentage of every cent paid into the network, these games produce an ever-increasing jackpot that's triggered by a rare combination of symbols. These games may be linked between machines on the same casino floor, or between different casinos, or any combination of the two.

The largest progressive networks regularly produce jackpots in the millions of dollars. These games are responsible for some of the largest jackpots in the history of American gambling. Progressive games like Slot o Mania are globally-recognized brands that carry a lot of player appeal. Though these titles' huge jackpots are tempting, these games generally give the casino a much bigger advantage than non-progressive machines.

Any machine that carries the image, voice, or other aspect of a licensed character or property is a "licensed slot." To put it in layman's terms, if the game has Batman's face on it, or features the voice actors from the latest Marvel film, or is based on the action of a classic board game like Monopoly slots, it's a licensed game. The appeal of these games should be obvious – people like familiar properties. Are you more likely to play a generic slot game or one based on the characters from Friends? Most Americans would be at the Friends machine in no time flat.

First popularized in the brick and mortar casinos of Las Vegas, these slots are now among the most popular online titles as well. Gamblers recognize brands and are influenced by marketing just like anyone else, maybe even more so. As long as licensed theme games are bringing in money for casinos online and on land, designers will continue to sink money into these properties.

Skill games is a loose category that includes a variety of machine games that don't replicate the exact playing style of slot or video poker machines. Some people will never recognize skill games as slots. However, casino management seems to think of them as the same type of game, since they're often grouped together on the casino floor or in online casino categories.

A skill game is a game in which you're rewarded for your skill. An example would be a video game in which you play a hunter shooting animated ducks. The more ducks you're able to shoot, the more you earn. These games take most of the luck element out of machine gaming, and much like video poker, reward players for being good at something. These games are catching on, as a younger and more tech-savvy audience enters the casino. For now, though, these titles make up a tiny percentage of the total slot gambling market.

Myths About Slot Games

Now that you know the basics of how the games are designed, built, and played, we think it's prudent to undo some of the damage done by slot machine myths over the years. For whatever reason, these games attract an inordinate amount of myths, the majority of which are totally unfounded. Believing in some of these myths will impact your enjoyment of the games, not to mention your potential profits.

Let's dispel four of the most insipid gaming machine myths:

Some people believe that slots will pay out at different rates depending on how recently a big jackpot has been claimed. You'll often hear people say that machines "tighten up" or "go cold" after paying out a jackpot. Some people believe that machines must be in "balance," meaning they have to take in as much as they pay out. This also leads people to believe that machines which haven't paid a jackpot in a while are "due" and more likely to produce a big win.

But all of the above logic is based on a flawed assumption. Every spin (or virtual spin) is an independent result. A machine's odds are always the same, regardless of previous outcomes. The random number generator that operates at the heart of modern slots has no memory of previous results. Machines aren't hot or cold – they produce random results independent of one another.

The thinking behind this one is plain enough. Since casinos give away free stuff to slot club members, the machines are programmed to recognize club members and reward them with less frequent wins. Or so the theory goes. Of course, this is patently ridiculous.

Casinos make a mint on slots players. Slot profits are so big, giving away a hot dog or a comp'd room here and there makes absolutely no difference to their bottom line. In fact, the slots club at your local casino is probably a major revenue producer. Why would they want to penalize the players that put them in the black every month?

Your odds are the same whether or not you use your club card. Actually, we think there's a strong argument that your odds are a little bit better when you use the card, since any freebies the casino gives you are a tiny slice into their advantage.

This bonehead myth is pervasive. We guarantee you know lots of people who really believe this to be true. According to this theory, the casino has employees whose job it is to monitor slots on the floor, then remotely alter their payout percentage or other features in order to achieve the aforementioned "balance." Usually, this line of thinking ends with something like "You'd better be friendly to the casino staff, and tip them really well as often as possible, or else they'll use their special remote control to wipe out your profits."

The truth behind this myth is a bit more complicated than it may seem. While it is NOT true that casinos attempt to "balance" their machines using a remote control, taking out their anger on player's bankrolls, it is true that some new-fangled slots can be altered remotely. However, this is an experimental practice that you'll find in a handful of casinos, and it is heavily-regulated.

The state of Nevada, concerned about the implications of these so-called server games, passed a hasty law that says that a machine cannot be altered by remote unless they've been fully idle for at least four minutes. At that point, the game's display indicates that it is being serviced – that means the game can't change in the middle of your playing session, without a long idle period and big flashing message.

But let's be honest – this myth isn't about experimental slots. The myth contends that every slot on the casino floor is accessible by remote. The fact is, these machines have to be taken apart to be altered. If a casino wants to change a machine's odds, it has to send an employee to physically crack the game open and swap out a computer chip. If you think the staff can do all that without alerting you, you're the world's least-observant gambler.

Plenty of people who scoff at the above myths still believe this garbage. We're not sure where this myth began. Maybe it was even true at one time. But our experience proves that in modern casinos there is no correlation between casino traffic and machine odds.

If anything, some casinos do the reverse of what's described in the myth above. In Atlantic City, for example, you'll often find banks of video poker machines in otherwise-ignored corners, away from the traffic and (relatively) clean air. Not all video poker games have spectacular odds, but on the whole, the game gives the house a smaller advantage than slot games. Why "hide" them in the back corner, if not to shoo people away from these lower-edge machines?

We don't totally shy away from this line of thinking – some slot games are undoubtedly tight, compared to the industry standard. Any location where you're part of a captive audience, like a bar or in the Las Vegas airport, is likely to play host to an incredibly-tight slot game or two. You should probably avoid slot and video poker machine games in lobbies and bars, which we suppose are kind of "high-traffic areas." Still, when you have to stretch a myth that far to make it true, is it really true?