A Guide to Online Slots – How Do They Work?

Whether it's the clink of a coin in a Las Vegas ‘one-armed bandit' or the catchy tune of an online game, slots are one of the first things we associate with gambling.

The statistics back this up: slots machines now make up the majority of land-based casino revenue, according to academics (Dow Schüll (2012), Boylan (2016)), and advances in game technology means their virtual cousins are often the showpiece of the best online casinos, too.

With technology playing a bigger role in our lives each year, online slots now compete with, and probably outrank, their land-based equivalents in terms of range and popularity. There are more virtual titles than ever before, and online casinos often make them central to their promotional campaigns.

If you're thinking of trying out an online slots game for the first time, or even if you're a slots veteran, it's a good idea to understand how these games work, and the perks and pitfalls you might come across while playing them. This guide aims to fill in those gaps in your slots knowledge.

What is the history of slot machines?

If you're eager to find out the origin of slot machines, then your search will take you a long way back in time: back to 1890s USA, to be exact. This was when rudimentary gambling devices started to appear in New York bars, in which players could insert a nickel, pull a lever and get random poker hands that sometimes delivered prizes based on the outcome.

Charles Fey took this idea further when he invented the famous Liberty Bell machine – a simpler mechanism which replaced the cards with reels of symbols and paid out the jackpot when the player landed three consecutive Liberty Bell signs – icons that we still see on today's titles.

The machines were banned for several years in California due to their addictive nature and state anti-gambling laws, but it didn't stop them springing up in other states along with many copycat versions. To get around the law, one of them, the Operator's Bell, gave out different types of fruit-flavored gum as a prize, which led to fruit symbols that told the player what they had won. The fruit machine was born, and this led to the classic slots games that many developers still create today thanks to popular demand.

Slots weren't just confined to fruit machines, however. In the early 1960s, Bally Manufacturing Co. created Money Honey, the first fully electromechanical machine, which came with an automatic pay-out of 500 coins when the player hit the jackpot. The lure of money combined with their ease-of-use attracted more and more players until slot machines became a regular feature at gambling hotspots such as Las Vegas and Atlantic City.

It was at the Las Vegas Hilton that the world saw the first-ever video slot in 1976, and it quickly became a feature along the famous Vegas strip, while IGT became the first company to mass-produce the machines a couple of years later for use across the Unites States.

As technology progressed, so did slots machines. The great leap from land-based machines to the World Wide Web began as we approached the turn of the century with Microgaming releasing Cash Splash in 1998. The graphics were rudimentary and the gameplay basic, but it signalled the start of a revolution.

Over the course of the 21st century so far, online slots have progressed rapidly with many modern video slots offering immersive graphics reminiscent of a PS4 or an Xbox One game. Players can now choose from hundreds of thousands of titles covering every theme you can think of... and more.

What's the difference between traditional slots and online slots?

It's easy to think of coin-operated slot machines and virtual slots as completely different, but the two have a lot in common. Online slots have been based on the traditional versions since their inception, after all.

The most important thing to remember is that reputable online and offline games use the same technology to ensure fair treatment of players. This is known as the Random Number Generator (RNG), a mechanism that operates without bias and doesn't remember previous bets, so you'll always have the same odds of winning. Both land-based and virtual games are bound by similar regulations, too, depending on the country they're in or which licensing authority they adhere to.

You'll also find that many online slots incorporate classic designs and features of traditional games, such as the fruit, 7s and bell symbols mentioned earlier. They generally follow a similar reel format and pay-out system, with the three- and five-reel designs still the most common. However, game design is also where we can see the biggest differences between the two, as virtual slots offer a much wider range of options to players.

To start with, the sheer range of internet slot themes available for you to play is overwhelming, and it's simply impossible to play them all. You can find games dedicated to everything from karate pigs to a machine-gun unicorn online, while you might only have a handful of real-life games in your local region.

Such a wide range of games and advances in technology means you can also find stunning graphics online. Video slots offer detailed storylines and cinematic sequences that immerse the player in a virtual world, to the extent that they're often compared to video games from a few years ago. On the flip side, immersive gameplay and special effects aren't quite as good as the buzz of the playing in the atmosphere of a real casino for some people.

Online games offer more sophisticated features, too. Megaways slots are a great example of this, sometimes offering over 100,000 ways to win per spin, much more than the 20-40 paylines common in land-based games. You'll also find more in-game features online, including progressive jackpots that get bigger every time players stake money, resulting in some enormous winning prizes. We can also expect a higher RTP from these slots overall, although this isn't guaranteed.

HTML-5 technology has also transformed the way people can play internet games — users can play on mobile-friendly casinos while travelling, for example — meaning player time, and money spent, can be much higher than games in bricks-and-mortar casinos.

Note: Online slots also benefit from promotional tools that are simply beyond the reach of traditional games. High competition between virtual casinos means you can play their slots for free before committing money, and you can use online casino bonuses as an extra chance to win cash prizes. Both are useful ways for the casino to attract new custom and are very popular with players.

However, the above advantages of online play present a big downside. The simpler it is to access a game, the simpler it is to spend money. Add this to the fact that spending electronic money is easier than parting with coins and notes — most online casinos offer many e-payment methods — then it's easy to see why virtual casino games have contributed to a rise in problem gambling. Also, internet players are often locked away in their houses, away from concerned friends who might notice symptoms and offer help. For this reason, it's especially important to be aware of safe gambling practices while playing online.

To summarize, while both types of games were born from the same concept, online slots have evolved to a point where we should consider them to be very different – in both positive and negative ways. Enjoying the benefits they bring, while following healthy gambling habits at the same time, is crucial towards having a safe playing experience.

I keep seeing terms like RTP and Variance when I browse through slots games – what do they mean?

If you're looking for the best possible slot-playing experience, then it's essential that you understand how RTP (Return to Player, also known as the pay-out ratio) and variance work.

Online casinos exist for one purpose above all – to generate profit. For this to happen, they need to be certain that they will make money from their games. They make sure of this through the house edge, a mathematical advantage, per game round, built into the game's mechanics that is expressed as a percentage of the total stake.

If the casino takes the house edge, then the rest of the stake is what the player can expect to earn over the same period. This is the RTP, or Return to Player.

The RTP of online slots typically falls between 92% and 99%, and we can look at a quick example of a slot that has a 95% RTP and, therefore, a 5% house edge.

Staked amount $100
Expected long–term winnings $95
Expected long-term casino profit $5

A game's variance, or volatility, tells us how much our bankroll is likely to change during our playing time, and how long we can expect it to last.

A low variance slot is likely to give you regular, small wins that, with the house edge, means that your balance doesn't go up or down much.

One with high variance, on the other hand, will give you rare big wins that can boost your balance to extremely high levels, but the scarcity of those wins means you can also lose it all very quickly.

While finding the exact variance of a game is difficult, it's quite simple to adjust it. With slots, the most common way is to alter the number of paylines. Changing it to just one and boosting the bet per line, means the odds of you getting a win in that line are shorter, but you might get a higher win.

Note: Many slot games also offer a double-up option for each win, often based on a black/red option. Playing this causes volatility to rocket as you're operating on a 50/50 basis.

Of course, remembering that you're much more likely to lose money this way is extremely important, and you should only do this with funds you can afford to lose — like with all types of gambling.

What will playing slots be like in 10 years?

Like with any online activity, technology is set to play a central role in slots development. In ten years' time, the games you play on are likely to look very different to the ones around today.

Video slots, many of which are already an exciting gaming experience, will incorporate elements of Virtual Reality (VR) so that you feel as if you're walking into the game itself, possibly with the reels on a virtual wall in front of you surrounded by super-realistic scenery. Advances in Artificial Intelligence (AI) might allow you to interact with the game's characters, who automatically respond to your actions and game results.

It could mean that jackpots and bonuses become even more elaborate, with extra storylines and outcomes added to make them ever more exciting.

However, highly evolved games will also come with some extra responsibilities to protect player safety. A more immersive game might lead to further rises in gambling addiction as players detach themselves from reality. We've already seen governments introduce new legislation to curb the rise in problem gambling that is said to come from increased online play - limiting the use of casino bonuses and banning credit cards, both features of the digital era, are two such examples of this.

Note: Players in ten years may benefit from enhanced online safety thanks to increased awareness of these problems, while also enjoying the superior graphics and gameplay of futuristic slots games.

Whether the above happens or not, the one thing we can guarantee is that there will be even more online casino sites than now, just like everything else on the web. Understanding the purpose of slots and how they function will make it easier for you to choose from the wealth of options available and have the safe gaming experience that you're looking for.

Niklas Wirtanen (1)

Niklas Wirtanen

My name is Niklas Wirtanen, I work in the online gambling industry, and I am a professional poker player. Thanks to my years of experience in online casinos and other types of gambling, I've gained a thorough understanding of the ins and outs of this industry, which I decided to share through the Vegas Expert website. I hope my expertise will help make your gambling experience better.

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