All the Different Online Slot Machines Explained

Ever wanted to know the difference between classic 3 reel slots and 5 reel video slots? Get to know all the different types of old and new games available including in-game features and jackpots.
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Online slot machines have exploded in popularity in recent years. The different types of online slots have grown along with it. Players today have a wide selection of game types to choose from, but all that choice can make things overwhelming.

Online slot machines can be divided into two categories: classic 3-reel games and 5-7 reel video games. The 3-reel games tend to be more straightforward and simple to understand. More modern games are a bit more complicated, but deliver big on excitement and winning potential.

Let’s dig into those two categories before we dive all the way into all the different types of games available to you.

Classic 3 Reel Slots

Fans of nostalgia and simplicity are a match for classic 3-reel slots. Invented in the late 1800s, the very first slot machine was called “Liberty Bell” and featured five symbols across three reels. Liberty Bell’s symbols are iconic today, with many games featuring its horseshoes, hearts, diamonds and bells.You’ll find plenty of 3-reel options in online casinos. The games on the more traditional side will often have just one payline. This is usually straight across the middle row. Others have more paylines, so it’s a good idea to check the info section to find out before playing one of these games. Games in this category tend to include a free spins bonus, but no elaborate bonus features. That could limit the potential for excitement among players looking for more entertainment value.

5-7 Reel Video Slots

Classic 3-reel slots paved the way for more modern 5-7 reel video slots. Today, this type dominates the selection of online slots you’ll come across. These games often have a fuller experience for the player with stunning graphics and fun themes. They also feature more paylines than you’ll find on most 3-reel games.

How many more? Some can offer tens or even hundreds of thousands of winning combinations, which I’ll get to in a moment. Video slots also add depth and excitement with free spin and feature bonuses, wild symbols, scatter symbols, and more.

The 5-7 reel video slots is also where you’ll find the most variation in game type.

Cascading Reels

Cascading reels, also called tumbling reels or avalanche reels, include a fun twist that can increase your winnings. Winning combinations of matching symbols will disappear and make way for new symbols to fall from above. This occurs until there are no winning combinations left. That means one spin can result in multiple payouts and more chances to trigger the bonus features.

Some 6-reel cascade games will include an extra row above reels 2-5. Megaways games by Pragmatic Play are a popular example of this format.


If you were wondering how far slots have come in more than 120 years, look no further than Megaways. These games can offer tens or even hundreds of thousands of paylines and winning combinations. It’s pretty clear how Megaways got its name.

You might expect Megaways games to be low volatility because of the number of possible wins, but don’t be fooled. Megaways can be volatile and give you lots of dead spins. If low volatility games are more your speed, keep a close eye on how often you’re winning on Megaways games.

Infinity Reels

If 5-7 reels aren’t enough for you, how’s infinity? Yes, some online slot machines have reels that could theoretically stretch to the end of time, if you keep winning. 

Infinity Reels games are easier to understand than some of the others on this list. These are generally 3-reel games, but any winning combination produces a fourth reel for no extra wager. If a symbol or symbols that match a winning combo in the first three reels appears on the fourth, a fifth reel will be added. And so on until an added reel does not have a winning symbol.

With each winning reel that gets added, your win potential becomes massive. I’ve found Infinity Reels games to be more volatile than other types, but as always, individual experiences may vary.

Expanding Reels

If Infinity Reels grow horizontally, there has to be a type of online slot that grows vertically, right? Good guess. These are expanding reel games and there is some variety with this type. Games might expand reels randomly or by landing a specific symbol, like a wild that grows into a full reel. 

Some games might only offer expanding reels during bonus rounds. The benefit to playing this game type is, of course, more possible winning combinations or paylines. Again, pay attention to how these games align with your volatility preferences.

Ways Boost 

Ways Boost games are somewhat similar to Megaways in that each spin offers different potential ways to win. Ways Boost games, however, can include 2×2 and 3×3 symbols, and reels can even expand vertically or horizontally.

Chilli Xtreme Ways Boost by Playtech is one of the newest examples of this type. At the start of any spin, you have 4,096 ways to win. Conditions can change once the reels start spinning and you could end up with as many as 262,144 ways to win.

Jackpot Slots

Anyone who plays slots is looking for jackpots and they can often be found on any of the types listed above. Jackpots go even further to enhance entertainment and win potential of a game, so let’s jump into those.

Progressive Jackpots

A progressive jackpot is a pool of money that increases with each spin that doesn’t win the jackpot. Progressives usually include several different sizes. You’ll most often see these as mini, minor, major, and grand jackpots, but some games will have more. There is no set time for progressive jackpots to hit, so jackpot totals can skyrocket over a long enough period of time.

Fire Blaze & Mega Fire Blaze Jackpots

Fire Blaze Jackpots and Mega Fire Blaze Jackpots are exclusive to Playtech games and all slots in this collection include mini, minor, major, and grand progressive jackpots. To win a Fire Blaze progressive jackpot, you’ll have to first trigger the Hold and Spin feature. This happens when a single spin results in landing six or more special symbols with credit amounts or a star on them.

During the Hold and Spin feature, players are given three free spins to land an additional feature symbol. Each time a new feature symbol lands, the free spins reset back to three. The feature ends when three-straight spins fail to produce another feature symbol.

If you hit a star during the feature, it will reveal one of the progressive jackpots at the conclusion of the feature. The mini, minor, and major progressive jackpots can be won on any spin as part of triggering or playing the feature. To win the grand jackpot, you’ll have to fill each spot on the reels with the feature symbols before you run out of spins.

Mega Fire Blaze Jackpots work the exact same way, but include an additional type of feature symbol along with credit amounts and stars. Mega Fire Blaze Jackpot games are five reels with three rows, but when the Hold and Spin feature is triggered, an additional six rows are added above the bottom three.

Every row added to the reels is locked to start the feature. By landing unlocking symbols, players can put these rows into play. The objective is to unlock all nine rows to maximize the potential of a big win.


From the simplicity of classic 3-reel slots to the thrilling features of Megaways and jackpot slots, there really is a game for everyone. If you’ve stuck to more traditional slots, give some of the variations a try. It’s safe to say this list of types will only grow as time goes on. 

Don’t be afraid to try something new. If you’re in doubt at all about how a slot machine type works, just press the spin button. The game will take care of the rest and you’ll start to catch on.

As always, approach any type of online slots with knowledge of its return-to-player percentage and a sharp eye on its volatility as you spin. In the end, you might just come away with a whole new category of slots you enjoy — and hopefully some big wins, too.

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Author: Jay Adams
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