How Do Online Slots Work? A Comprehensive Guide to Understanding Online Slot Machines

We guide you through how Online Slots Work.

How Do Online Slots Work? A Comprehensive Guide to Understanding Online Slot Machines

Slots are among the most popular casino games, as they give you the chance to take part in games of chance based on diverse themes.

How do online slots work and what do you know about them before getting started? We’ll be looking at everything you need to know about the slot algorithms and how wins or bonus features are triggered.

How Are Slots Designed?

If you’ve played land-based slots before, you might be surprised at the number of different online slot presentations of the same type of game you can now find. While some have a retro feel, with several rows of classic symbols, such as fruits, over a few reels, the industry has seen an explosion in the different styles and themes used in recent years.

The first thing you’re likely to spot is the theme, as this is what determines the symbols used and the background images. The theme doesn’t have an effect on the slot mechanism at work.

You could play one slot based on pirates and another that’s got a fruity theme and discover that they work in exactly the same way, as the theme only covers the visual aspect and sometimes the sound.

Classic slot symbols such as fruits and playing cards are often used, but you’ll also see other images that vary according to the many themes that slots are based on.

When we look to see how slots work, we need to look first of all at the number of reels and rows they contain. This is where the symbols fall and while many slots have five reels, you’ll see some with three, six, or even different amounts from these. There are games that cleverly change the number of ways of winning on each spin, by adding, removing, or merging reels each time, with the Megaways™ engine range of slots a great example of this approach.

You could simply choose a slot that catches your eye because of its theme and start playing. We’re here to look at the issue of how online slots work when you start spinning them, so let’s find out next what you need to do to potentially grab a win.

How Do You Win on a Slot Game?

How do online casino slots work when awarding prizes? The aim of these games has changed little over the years, although new technology and ideas have been added to make them far more varied.  

With any slot, the idea is to get a set of matching symbols across the reels to trigger a payout. Do this and you’ll automatically receive a prize. It’s as simple as that and since the symbols fall into place, you can choose to simply press the start button and start playing without understanding any of the rules we’re about to look at.

Any win or features that you trigger are automatically credited to you. This is because each of these games has a paytable where all the symbols are listed with a value beside each of them.

The paytable tells you other important information such as how winning combinations can be formed. In some cases, you need to get at least three matching symbols on any of the defined paylines that sit across the reels while other games pay out on clusters of matching symbols that land beside each other. The more matching symbols that can be seen together on a payline or in a cluster, the bigger the win for you.

A wild symbol is used in a lot of slots, to make it easier to build a winning combination. This is because it’s a kind of joker that can replace any of the paying symbols to complete a win. Developers are increasingly adding different types of wilds – such as sticky wilds and walking wilds – to add more variety to their games.

Free Spins and Bonus Rounds

The previous section covered what’s called the base game, which is where you spin the reels and they either land in a winning combination or not. Many modern slots add an extra layer of gameplay in the form of a bonus round.

The most common type of bonus feature is a set of free spins, which are typically triggered by landing a minimum of three of the designated scatter symbols anywhere on the reels. The free spins round may involve some sort of enhancement from the base game, such as more bonus symbols or multipliers, or it might have exactly the same gameplay.

The paytable will explain any bonus rounds that are available. Some involve picking objects to try and reveal a hidden prize or getting respins for a second chance at a win.

With the number of features in slots growing all time, you should come across a few different bonuses to try. On the other hand, some simple slots only have the base game with no extra features at all.

How Much Can You Win Playing Slots?

We need to go back to the paytable if we want to work out in advance how much we could win on a spin. Each of the paying symbols will have a figure next to it, which tells us what could be won by getting a group of these images in a win. If there are bonus rounds, the paytable is where we’ll see what they could be worth.

The amounts listed as the prizes are multiplied by the amount that you wager. This means that the final step to take before spinning the reels is choosing your stake. These games usually accept small stakes, but you should check the list of acceptable amounts before deciding whether to go ahead.

You should look out for multipliers, which are applied in certain situations in some slots. They could come into play when you enter the free spins round, or if you get several consecutive wins you could see multipliers start to get added to them, for example.

It’s worth looking out for the tumble or cascade feature. This is part of the gameplay in certain slots and kicks into action when you get a winning combination. After you get paid for the win, the symbols that make it up will disappear and new ones will fall into place, which means that you get at least one extra chance at winning on the same spin.

How Slots Work Online (RNG)

In the past, the results on mechanical slots were determined by the moving pieces inside them that caused the reels to stop at a certain, random point. When these games moved online, the developers had to look for a way of replicating this process digitally and ensuring that every spin is random using an online slot machine algorithm.   

Therefore, when considering how online slot work, we’ll start by looking at the random number generator or RNG. This is a sophisticated piece of software that ensures that the result of every spin is totally random. When you hit the spin button, neither you nor the casino knows if it’s going to be a winning spin or not.

This means that you can’t assume that several non-winning spins will be followed by a win, or vice versa. The RNG and online slot algorithm is such an important element of slots that it’s tested rigorously through independent checking carried out by certified testing companies to confirm that it works as intended.

What the Return to Player (RTP) Figure Means

While the RNG ensures that you never know what will happen on any spin, there has to be a degree of control over the amount paid out. Players wouldn’t want to play a slot that very rarely pays out, while the operators can’t afford to risk several jackpots being paid out at the same time.

It has weighted figures for each of the symbols to ensure that the lower-value icons pop up more often. The complexity of these calculations means that the best way for developers to work out how much they expect a slot to pay out is by running millions of spins and seeing what happens.

They can calculate a return to player (RTP) figure based on how online slots work in real life over a massive number of games.

The RTP is expressed as a percentage, so the closer it gets to 100% the more of the amount wagered by all players should get returned to them as wins. For example, if the RTP is 90% then every £100 should lead to £90 being returned in the form of winnings, in theory.

This doesn’t mean that you can expect to receive 90% back of all the money you gamble on a slot with this level of RTP. Since the RTP is based on a massive number of spins, you won’t know how much you might win if you play a few spins.

How Do Progressive Jackpots on Slots Work?

You might spot some eye-catching slot titles where a large cash sum is mentioned as the jackpot. How does this fit in with the details that we’ve looked at so far? 

Each slot will explain in the paytable or help section what you need to do to win this prize. It’s often paid on a random basis but some games will ask you to complete a bonus round or some other way of claiming this prize.

You’ll probably notice that the progressive jackpot keeps on climbing. This is because a small amount from each wager that gets placed is added to the total. Once a player triggers the top prize, it goes back to the original amount before starting to build up again.     

Myths About Online Slots

We can now look at a few of the common myths that exist.

The first is the idea that there are hot and cold slots, which means that they go through streaks whether they either win frequently or lose several times in a row. Some people use this theory as a way of trying to predict which game is “due” to pay out soon.

Since we looked earlier at online slot mechanisms, we know that there’s no way of predicting what a slot does next. It’s completely random, so knowing if a game just paid out or not doesn’t help us calculate what it might do next. You simply need to remember that these are games of chance where no one knows the result of the next spin.   

Another myth is that a slot that just pays out big won’t pay a big win again for a while. This is similar to the last point in that we have no way of knowing what the next spin’s result will be, so it’s possible that one win follows another.  


How do online slots work for UK players?

Slots are games of chances with a random outcome on every spin. The regulated nature of the British gambling market means that the games are all fully tested before being released.

How to play online slots for real money?

By funding an account with the regulated Paddy Power casino, you can start to play spins with real cash and try to win real prizes.

Can you really win money playing online slots?

Yes, the slot algorithm we’ve looked at ensures that every spin has a random outcome, so there’s no way of knowing when the next payout will be made or to whom. Everyone who plays has the same chance of winning.


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