Online Slot Machines Types

Home » All Slots » Online Slot Machines Types

Slot machines are probably the main attraction of any online casino, with very few exceptions.

It’s worth noting, however, that online slot machines derived from their real-life counterparts.

Brick and mortar slot machines have actually been around in some form or other since as far back as the 1890s. They have quite a fascinating history.

Classic Old Grey and Orange Slot Machine

The whole thing started in the United States of America with two different machines.

Both were in use in the city’s many bars.

One had five drums and 50 cards — the 10 of spades and jack of hearts were missing in order to favour the house — while the other had just three reels along with five different symbols.

Because the bell was the highest-paying symbol, this slot was known as the “Liberty Bell” slot.

The Advent of Video Slots

In 1976, the world saw the first-ever video slot, which was brought out by Fortune Coin, a Las Vegas company at the time.

The year 1996 saw the advent of the first bonus round in a video slot, which took slot machines to a whole new level of popularity.

The Origin of Online Slots

The year 1996 also saw the introduction of the world’s first online slot.

Once again, the first offerings available on the internet were subject to the technological limitations of the time.

They would seem quaint, slow, and cumbersome to the average contemporary slot player.

Once again, however, at the time, they were very much a groundbreaking effort. InterCasino, the first online casino, had only 18 games when it first launched at the time.

Amazingly, they are still around to this date, and still doing business as the world’s longest-running online casino.

Online Slot Software Providers

Following that, Microgaming started up as the world’s first software provider working for the online gaming agency.

Microgaming Sofware Provider Blue and Green Logo

This is another illustrious brand that is still around today. What’s more, it is still thriving and providing top-notch games in use in online casinos.

Microgaming alone has released over 500 online slot offerings in this industry over the years.

As time has gone on, online slots have evolved greatly. They have actually gone way beyond the technical limits of mechanical and even the video slots of previous decades.

This is not surprising; it was to be expected.

However, the first online slots were reproductions of brick and mortar slots, including early types of slot machines, and followed them closely.

Furthermore, these formats of slots are still popular to this day. New titles in even the earliest styles of slots are still being released as online slots.

And so, without any further delay, we will look at what offerings players have as far as online slots go:

Online Slot Machine Types

Three Reel Slots – Classic Slots

3 Reel Online Slot Machine

These are generally faithful reproductions of earlier classic slot machines of the “one-armed bandit” variety.

In some cases, there is even a virtual lever that you must “pull” using a touch-screen or similar.

Often seen also are many of the same themes of the classic slots, and especially, the same symbols slot players have grown to know and love over the decades.

These include things like the heart, the diamond, the spade, the horseshoe, the bell, the 7, the gem, the crown, and the clover.

They also include the famous “Bar” symbol, as well as a vast cornucopia of fruit symbols.

Four Reel Slots

As you explore our selection of 4-reel slots, you’ll notice that most of these games take on the fruity theme typical of bar or pub slots.

While some are based on ancient Egypt (one of the most popular themes among both players and producers), or the natural world, be prepared to see plenty of juicy, colourful fruits appear on your screens.

You will also notice that while most 3-reel slots only have 5 paylines, 4-reel slots create the perfect terrain for more complex games.

In this section, you will find slots with 10, 15, or even 20 paylines and, consequently, slots that offer many more chances to take home a fabulous prize.

The bonuses offered also tend to be more generous and diversified than those you can find in 3-reel slots.

In fact, you are more likely to find slots that offer free games, unlockable with the right combinations of symbols.

However, don’t forget that extra modes and mini-games are usually only available with slots that have 5 or more reels.

Five Reel Slots

In online casinos, slots with five reels are very common, and, as mentioned above, these types of slot machines still resonate with a modern slot-playing public the world over.

They are, in fact, still the most common variety of online slot up to the present day.

A typical five-reel online slot has anywhere from 10 to 30 paylines, sometimes more. Also, free spins features are almost always de rigueur with this type of online slot, as are bet multipliers.

Slots With More Than 5 reels

Over the years, online slot providers have started to think outside of the box. This meant, primarily, that they were growing tired of the five-reel format and wanted to try some new things.

The experimentation was a slow process until just recently, with new ideas coming bit by bit.

Six or Seven Reel Slots

The first thing developers did was to expand the slot horizontally. This meant developing 6×3 or 7×3 layouts.

This was often done in such a way that you could have a longer payline which gave a potentially larger payout.

These larger layouts also mesh nicely with things such as the wild symbol or the scatter symbol, which will also be discussed more fully later on in this article.

Fruit-Themed Slots

Fruit slot with 4 reels

Players around the world are almost certainly familiar with this array of symbols, which started with just cherries, an orange, a watermelon, and an apple.

These days, fruit-themed slots often have some modern surprises attached to them.

This could be something as simple as a nice animation. Often, another fruit is included as well in the milieu of symbols in an online slot.

Megaways Slots

Megaways slots are a great example of an online slot that would be impossible to implement in the real world.

It could be said that Megaways slots are a kind of pinnacle of development of the online slots to date.

The first online slot of this type was Dragon Born. This slot came to be in the year 2015 and was released by Big Time Gaming.

Big Time had been founded four years earlier in the year 2011 in Australia as an online software developer.

The developer wanted to push the envelope as far as it could as far as online slots go.

How the Megaways Concept Works

Online slots of the Megaways type have a number of symbols that can differ per reel.

This means that the number of paylines can vary considerably with each spin.

Furthermore, the number of paylines can be incredibly high. Some recent versions of Megaways online slots can have over a million paylines, depending on each individual spin.

Most Megaways slots will payout for symbols that appear on adjacent reels, no matter where which explains why there are so many possibilities for payouts with this type of system.

Video Poker

Video Poker Played on a Computer Screen

Video poker is worth mentioning, as it is a variation of slots and is also wildly popular in many circles.

In many ways, video poker is half slots and half poker.

Almost always, video poker games have the same spin mechanics as any other type of slot mentioned in this article.

In the case of video poker, the “spin” gives you a poker hand.

In this sense, video poker is not like traditional poker, in which you play against other players or a dealer.

In video poker, payouts occur according to a pre-determined pay table.

Since there are almost never any wild “cards” in video poker, the royal flush pays out the most.

On top of that, video poker itself has dozens upon dozens of variations.

Arcade-Style Online Slot Games

One of the most recent and exciting trends in the online slot industry is to add more arcade-game-like elements to the experience.

In fact, sometimes this is taken as far as making the game more like an online arcade game where you can play for money, with just some elements of an online slot.

Online Slots and Jackpots

Animation of a Slot Machine Hitting a Jackpot

Slots are sometimes linked together, and each bet has a certain percentage of it go to build up a jackpot.

At any time, a lucky winner can win it all, although, naturally, the odds are very slim in these cases.

Jackpots were pioneered in the brick and mortar world, where networks of machines were connected together to allow progressive jackpots to build.

These networks were very local in nature at the time.

This category is yet another area in which Microgaming can boast of being the first people to launch a product. They released the first online slot with a jackpot, called “Cash Splash.”

However, this game’s payouts paled in comparison to what would later come down the line.

The record for the biggest jackpot payout in an online slot, however, goes to Mega Moolah.

On one spectacular occasion, Mega Moolah paid out a whopping 17.9 million EUR to a lucky winner!

Bonus Games in Online Slots

As mentioned previously, the first bonus game on a (brick and mortar) slot machine was available in 1996, the same year that online slots started out on the internet.

In today’s online-dominated world, it’s almost rare to see an online slot that doesn’t offer some kind of bonus game or bonus round feature.

These are often accompanied by flashy graphics, animations, and music, designed to draw the player even further into the game.

There are so many different types of bonus games available these days, that it is completely impossible to give an exhaustive list of even a fraction of them.

The Hold and Respin Feature

This feature is another new trend in the world of online slots. It is almost always a feature of bonus games within these slots, although it does pop up on occasion on respins.

This type of feature can be used in many different ways.

One example of the common use of the hold and respin feature is the “pick a prize” mechanic, which appears to greatly increase player engagement.

Other uses of this feature are to give credits, advance progressive jackpot, or conceal other games within the main game in online slots.

Multipliers in Online Slots

Many of the best online slots have made multipliers a key element of being able to get significant winnings on them.

To wit, these are often set up with some sort of a “ladder” mechanic, allowing the player to obtain 2x, 3x, 4x, 5x, 10x or even higher multipliers. Often, they will go all the way up to 1000x or more, as the case may be.

Developers also have the option of making these multipliers only apply to winnings, or to make them also apply to other things like line bets or total bets.

Often, multipliers are applied in very complex ways. For this reason, it’s recommended that savvy players read up on the rules of the games they play.

Often a free spins round or bonus round or game will have its own special multiplier.

Once again, this multiplier can be sui generis or can interact in any number of ways with the multiplier featured in the main game.

Another common tactic of developers is to include a multiplier with one of the many different types of wild symbols out there.

Wild Symbols in Online Slots

A Example of a Wild Symbol Found on an Online Slot ( Bell Symbol)

The concept of a wild symbol is a bit of a carry-over from other games such as poker, but it has been an integral part of online slots since its inception.

In general, this concept is much simpler and more straightforward in its implementation than many other concepts. A wild simply substitutes for any other symbol in the game.

This almost always means the symbol with the highest value and/or that which would lead to the highest payout.

In some online slots, wild symbols have an intrinsic value, which can increase player winnings in often unexpected ways.

Another common tactic of developers is limiting the appearance of these (or any other) symbols to specific reels, or something else similar.

And, finally, some online slot games even have two or more wild symbols incorporated into them.

Stacked Wild Symbols

Many online slot games offer this special feature, which can cause massive payouts if it lands in the right combination.

In addition, these symbols look like their names would suggest they look: like various symbols stacked upon each other.

This means also that they inevitably cover more of the reel, sometimes even covering the whole reel.

Stacked wild symbols, or expanding wild symbols, as discussed immediately below, tend to increase the volatility of a game because of their payout potential.

Expanding Wild Symbols

Expanding wilds are very similar to stacked wilds. The difference is that an expanding wild simply takes over the reel on which it appears.

The only symbols it doesn’t replace (usually) are the scatter symbol and the bonus symbols.

This means that the whole reel becomes one big wild symbol, which often activates payouts on a large number of paylines.

Expanding wilds are a great opportunity for developers to use clever graphics, animations, and sounds to illustrate what has just happened in the game, often to great delight by the player.

Sticky Wild Symbols

Sticky wild symbols also do just as their name suggests. They stay in position for the next spin, or determined number of spins.

While perhaps not as likely to lead to big wins as other types of wild symbols, nonetheless, they are a big upgrade over the normal wild symbol that sits in one position and then disappears.

Sometimes, the sticky wild triggers a round of auto-spins while it is in play. Other times, it stays there and the player spins normally.

Sticky wild symbols are also often reserved for free spins rounds or bonus rounds.

Shifting Wild Symbols

Shifting wild symbols are similar to their sticky counterparts. The key difference in shifting wild symbols is that they change location with each spin.

Often, what will happen with a shifting wild symbol is that it will appear on one of the outer reels (left or right) and then work its way across as the player keeps spinning.

It is also possible to combine the sticky wild mechanic with the shifting wild mechanic. This means that a wild symbol will stay in the same spot and then afterward start moving around the reels.

Another somewhat rarer version of the “shifting wild” symbol is the “walking wild” symbol.

This is simply when the wild symbol appears anywhere and “walks” off the reels in one direction only during auto-spins until it “falls” off at the edge.

Overlay Wild Symbols

Overlay wild symbols are similar to stacked wild symbols. The main difference with the overlay wild symbols is that they don’t have any specific shape or form to them.

They also often have the ability to overtake a whole reel like stacked or expanding wilds can. For this reason, they often trigger lots of winning combinations.

Contagious Wild Symbols

Another unique mechanic that’s a bit newer than the others is the contagious wild symbol. This symbol “infects” the symbols adjacent to it, turning them into wild symbols as well.

As such, it could be considered a limited type of expanding wild symbol.

Naturally, these type of wild symbols has a lot of variations to it. Some times of contagious wilds go in various directions at once.

Some will touch symbols diagonally next to the contagious symbol, others will not.

Scatter Symbols in Online Slots

An Example of a Scatter Symbol Found on an Online Slot ( Strawberry Symbol)

The other type of symbol that is rare and important in online slots is the scatter symbol. It functions in a distinct manner from the wild symbols, though.

In fact, scatter symbols in most online slots that have them tend to be the best-paying symbol on average of all of them.

The scatter symbol also has a much deeper history than the wild symbol. The cherries symbol mentioned previously in the early fruit-themed slot games is widely considered to be the first scatter symbol ever.

This is because it paid out no matter what the other symbols were doing. This is how the name “scatter” came to be, in fact.

The symbol can be “scattered” anywhere, but it will still have the same effect.

Another common feature of scatter symbols is that, if enough of them appear on the same layout, they will generally trigger some special feature.

This special feature is usually a bonus game or similar. Often, the more scatter symbols have appeared, the better the bonus game will be.

Scatter symbols also tend often to have other bonuses such as multipliers built into them as well.

Identify the Scatters

Wise players will make sure to know what the scatters are exactly. This means, what they look like in all of their potential various forms, and also what the scatters can do.

A player will want to know what effect scatters have depending on how many of them appear at any given time.

Scatters are Like Snowflakes

This is especially important because the actual function of a scatter in gameplay can vary greatly from one online slot to another.

There is definitely variation in wild symbols, as can be seen above by the various types described.

However, with scatter symbols, the potential for variation is that much greater, because of their nature.

Also, a surprising number of online slots these days often combine the wild and scatter symbols into one multi-function symbol.

However, it could still be said that the vast majority of online slots have both types of symbols.

Interaction of Scatter Symbols and Bonus Rounds

Scatters usually interact very closely with bonus rounds or free spin rounds. This is what makes them so relatively unique; they are affected by the nature of the bonus rounds the particular online slot offers.

For example, it’s possible that, in one game, the number of free spins a player gets is determined by how many scatter symbols appear at a time.

In another game, as long as three or more scatter symbols have appeared, the number doesn’t matter at all.

Or, as another example, in one game, scatter symbols trigger a spin of a wheel, which determines the kind of bonus round which will be played, from among several options.

But in yet another game, the amount of scatter symbols that appear at once will determine which kind of bonus will be triggered.

The Newer the Slot, The More Complex the Scatter Mechanics

In general, the newer the game, the more complex it tends to be. This is definitely the case with scatters.

In fact, many earlier online slots don’t even feature scatter symbols, and just focus on wilds. In some cases, especially with very early games, often neither of the two features are present.

These games would generally be classed as low-volatility and feature more frequent but lower payouts.

Learn the Scatter Mechanics by Playing Demo Mode

The best way to learn these types of features of games properly is to play the slot in a “free” or “demo” mode.

Almost any reputable online casino will offer some sort of an option like this, where you can play and learn the ropes of a game before deciding to risk real cash on it.

Interactive Slots (I-slots)

Interactive slots add a whole new dimension to the online slot experience, giving players much more choices than simply spinning.

In many cases, interactive simply allow for the spinning of different reel combinations. In others, things are even more elaborate, often taking on one or more elements of an adventure-type video game.

Interactive slots are often, for this reason, much more reliant on player skill, and as such, are almost a completely different category of game.

They do tend to retain key elements of an online slot, however.

The idea is to draw the player in even more than previously and to make them feel as if they are participating in an actual event so that they don’t get bored of the experience too easily.

Naturally, mini-games are very very common within interactive slots. One game will often have several mini-games hidden within it.

Plots and Online Slot Themes

These types of online slots often feature stories with plots that are advanced by in-game actions as well. This makes the experience more immersive for most players and has proven to be quite popular.

Game plots for online casinos in any case have been getting more and more common.

A lot of the more modern online casinos feature slots in which the player becomes a protagonist, or stands in as a contestant on a virtual game show of some sort.

This appears to be what modern online slot players are demanding more and more.

Another option for online slot developers, to even further increase elements of immersion, is to combine interactive elements with virtual reality elements.

Virtual Reality Slots, or VR Slots

Animation of a Virtual Reality Slot

Perhaps the most exciting of the newer trends in the online slot industry is the inclusion of increasingly sophisticated virtual reality technology.

The applications of this type of technology are obviously extremely broad and numerous as well.

One great example of a common application of virtual reality in online slots is to place the player in the middle of a prestigious brick-and-mortar casino.

This can go as far as laying out large sections of the casino, so that the player can, for example, go to a virtual bar, or virtual cash out window.

Sometimes, there are even virtual waitresses or a virtual view of a city skyline outside the simulated casino’s windows.

Another possibility for virtual reality is to place the player in an environment that has to do with the theme of the online slot itself.

Indeed, these two categories are the two main categories contemplated by game developers using virtual reality.

Graphics, Sounds and Animations in Online Slots

Since the first online slot became available to the public in 1996, things have improved exponentially in the area of graphics, sounds, and animation.

These days, each slot really does seem to be better than the previous ones in terms of how a theme can be detailed with clever design.

Online slots often feature full musical soundtracks as well, often interactive soundtracks that react directly to game events.

Online casino providers and casino gaming providers are now able to hire top-notch experts in the different audio and visual fields.

This has led to an almost cinematic experience for players these days. The best part about all of this is that players are now absolutely spoiled for choice.

A player can go in literally seconds from a classic fruit-themed slot offering to a modern-themed slot with interactive elements to a Megaways slot with a million possibilities for paylines.

All of these offerings have incredible audio and visual elements to enhance the player experience.

A player can also, for example, go from a Viking raid to exploring an Egyptian Tomb to being a crack tennis player at Wimbledon in almost no time, all from the comfort of said player’s computer, tablet, or even phone.

Playing Online Slots on Mobile Devices

It’s no secret that the industry is moving quickly towards mobile devices.

In fact, it is now estimated that the majority of all online gaming of any nature now takes place on people’s phones.

As a result, this has pushed providers to make sure that their games are optimized for use on mobile devices.

In some cases, it could be said that some online slots run more smoothly on phones than even on much more powerful desktop computers for this reason.

Many times, online casinos have their own proprietary apps for use by players.

However, this is starting to trend more and more in favour of simply optimizing a website for mobile use, and having players access it by using the web browsers in their mobile devices.

This is because users are concerned more and more about the proliferation of apps on their phones, which often slows the device down and leads to potential conflicts, as well as gobbling up memory which, in many cases, is a scarce commodity on smartphones.

Surprisingly, even virtual reality is often possible on mobile devices and is starting to be implemented more and more by savvy providers.

This is important for providers and players, as mobile gaming is likely to gain even more market share in the near future.

Future Online Slots

Online slots have come a long way from the 1990s, and can now be considered a very mature and successful industry.

There is no doubt that the industry will continue to grow, almost no matter what.

However, and corollary to that, regulatory bodies like the UK Gaming Commission are likely to pass more and more legislation affecting the online gaming industry, and online slots along with it.

More Immersion

Technology is likely to keep moving forward for online slots. This means in practical terms that the experience will get more and more immersive for players.

Especially, virtual reality-based online slots will almost certainly tend to get more and more common.

It is also very likely that the traditional mechanics of online slots will be tweaked more and more.

It’s probable, in fact, that entirely new slot mechanics will be devised by smart and savvy developers, in an effort to stay ahead of the pack for players’ attention.

Furthermore, we are also likely to see ideas that are currently popular developed further, more deeply.

For example, for whatever reason, people tend to love Egyptian-themed slots.

So, for that reason, developers are likely to keep on releasing slots with that sort of a theme, but with new twists, new mechanics, new plot devices, among many other things.

Multi-Stage Online Slot Games

Another distinct possibility would be for savvy developers to start creating online slots with more than one theme.

What’s more, these slots could be activated based on gameplay, where the game morphs from one theme to another.

Or, for example, the game itself could advance through the history of all online slots as you progress through it.

That which is mentioned in the above paragraph could also be nicely paired with some of the latest virtual reality technologies.

For example, instead of just playing a virtual game, one could enter a virtual casino, with outcomes of one game affecting all the other games.

This could ultimately be tied in with things such as progressive jackpots and the like, and be made multi-player experiences.

Who knows, maybe in the near future we will see things like the world’s first PvP online slots?

The possibilities alone those lines for online slots can be truly endless, as technology opens up more and more doors.


What are the best types online slots?

As can be imagined, there is no hard-and-fast easy answer to this question.

This is primarily because individual tastes can and do vary quite a bit from person to person, and even from day today.

A good player constantly tries out new slots and decides on his or her own what is best for him or her, and what personally resonates the most.

Good questions for players to ask themselves are:

  • Do I like high, medium or low volatility games?
  • Is the added thrill of a jackpot important to me as a player?
  • What kind of themes do I like best?
  • Do I like simple or complicated online slots?
  • Is virtual reality of interest to me?
  • Are interactive elements in an online slot of interest to me?

Experts do, however, put good lists of the best online slots out there from time to time.

It would be a great idea for savvy players to check back to these lists from time to time to see what new and great things could be coming down the pike.

Final Word

Gambling has existed in some form or other for probably as long as civilization itself has existed, and it’s something that has constantly been evolving and changing as the environment around it has changed.

What’s more, slots have been able to keep up in spades as time marches on.

As such, the slot machine has a mere history of fewer than 130 years, and online slots are only a quarter of a century old, as of the time of this writing.

Even compared to other popular casino games today, such as roulette or baccarat, slots are clearly a newcomer to the industry.

In fact, one could even say that the venerable slot is a product of modern technology.

As a result, it has also scaled with new technologies perfectly, from its Industrial Age origins through the modern and now the digital ages.

However, slots and technology do tend to go hand in hand with each other in a big way!

This just goes to show, however, how popular slots are with the gaming public.

Despite their relative lack of history, they are the most prominent and important part of any casino today, online or otherwise.

They are a clear consumer favourite, with perhaps 70 percent or so of online casinos’ offerings being some form of an online slot or video poker.

Perhaps what is most interesting is how modern online slots with brand-new concepts do well, but re-creations of classic old slot games tend to also do just as well with players.

As a result, this shows clearly that slots will continue to be popular with players and casinos alike for the foreseeable future.