Ultimate Guide to Online Slots

Some people may think there’s nothing involved in playing a slot game – simply click the button and see what Lady Luck has in store for you on that spin. However, that doesn’t mean that players can’t benefit from knowing a bit more about a slot game and its features.

In this slots guide, you’ll find all you need to know about video slot games to help you have a better gambling experience at online casinos. With advice on how to play and win at slots, plus a full guide to the terminology, you’ll be all set to start spinning.

How slots work? The mechanics behind slots

How do online slots work?

Understanding what is at work behind the scenes can help you make better choices for which slot games are worth your time and money. And more importantly, which ones are not!

Even the simplest of online slots is actually a combination of sophisticated stuff that works together to ensure complete randomness and unpredictability. This means that players can be safe in the knowledge that they really do have as much chance of winning as anyone else.

Random Number Generator

Random number generator

A Random Number Generator often referred to as an RNG, is the clever software that powers slot games behind the scenes. It helps to ensure that any game has a totally fair and random outcome. RNGs are used across many industries for a whole host of applications which require completely unpredictable outcomes.

Having an RNG applied to a slot game helps it to come up with a sequence of truly unique symbols each time the reels are spun. The idea is to introduce an element of risk in the fairest way possible, ensuring that no one can predict what sequence the next spin will produce.

If we take the typical slot game which has 5 reels and 3 rows then the possible combinations reach into the billions. RNG software ensures that all those potential combinations have the exact same chance of appearing on every spin, regardless of the previous spin results, creating a fair game.

Different types of slots - Reels, rows, and paylines

Reels, rows, and paylines

To master the basics of how to play slot games, you just need to know this: reels are the vertical lines of symbols which spin around and rows are the horizontal lines across the screen.

The reels and rows can appear in different configurations but the most common have 4 or 5 reels and 3 or 4 rows. Just think of the fruit machine in the pub, basic video slots work just the same.

A pay line also called a bet line, is a pattern drawn across the game screen. These can be straight across, vertical, horizontal, or even in a funky zigzag shape. If a combination of symbols land on one or more of these lines it counts as a win. The amount you win will depend on the symbols and combinations which appear.

Spinning reels, rolling reels or cascading reels

In recent years, game developers have gone way beyond the fixed reels of traditional slot games. Reels can behave in various crazy ways to ramp up the gameplay and boost a player’s winnings.

Rolling reels, also known as cascading reels, give the chance for extra wins on a spin. Symbols disappear allowing more to drop down and replace them. This can mean that a single spin can just keep going to yield bigger winnings.

Slot guide - what are paylines?

Coin value, paylines and paytable

Coin value simply means the amount you are betting on each spin which is represented in the slot game as a coin. Players can vary their wager amount from spin to spin and most games have a wide range between the minimum and maximum coin value wager per spin.

The paytable can be found in the info tab of any video slot and shows the value and features of a video slot game. This is where players can learn how to trigger the features of the game for increased winnings.

Fixed paylines, explained above, are usually shown in the slots paytable. Some slot games might feature flexible playlines which allows the player to choose which ones are active during each spin. The more lines that are selected the higher the bet per spin needed.

243 Ways to Win
This payline method is seen in several slot games such as NetEnt’s slot Aloha! Cluster Pays. This concept means that there are no fixed paylines but wins are instead generated from 3 or more symbols landing adjacent to each other.

Win both Ways

This simply means that rather than pay lines just going from left to right players can ‘win both ways’ i.e. in both directions. You can assume that a slot just pays out left to right unless you see this specified.


Created by software developer Big Time Gaming, Megaways has become a popular way to win in modern slot games. It effectively means that every spin brings a random number of ways to win, sometimes up to a massive 117,649.

Basic rules for how to play slots online

There are some key things to consider before you get started with playing video slots at an online casino. This quick checklist will get you set up for a better experience, one spin at a time.

1. Decide the type of slot you want to play

There are a lot of different variations to the humble slot game available right now. Online slots have evolved way past simple bells and fruit symbol but they are still there if you want them! There is no one-slot-fits-all out there and one player’s favourite may not be another’s cup of tea.

Think about the type of game you want to play before you dive in. Using the advice in this guide you can get a feel for the options such as Jackpots or slots with complex features and bonuses.

Do you want high volatility with bigger potential payouts but less often or something at the lower end of the variance scale? The beauty of playing online slots is that you can make your play as simple or as advanced as you want to. The power is in your hands.

2. Play for free

Many online casinos give you the option to play the games for free. Obviously, this means that you won’t get to keep any winnings and the coins shown are just for fun. It’s a great way to try out a game to see if you like the look, feel and features before you put any of your own money in there.

3. Set a budget

When you are ready to play with your own money, it’s a good idea to set a budget before you start. That way you don’t start spending what you can’t afford to at the casino. Playing slots can be an expensive hobby and things can quickly get out of control.

Setting a budget also helps you to know how much you want to spend per spin to make the fun last longer. Most online slot games start from £0.10 per spin and go up into the hundreds.

4. Check the paylines and paytable

Look for the information icon in any slot game and it should lead you to the paytable. This is where you can get the lowdown on the value of the slot symbols, both high and low.

The paytable will also show you the paylines of that specific slot game so you can decide if it is the one for you. You might even get the option to choose how many paylines are active on each spin. Be aware that the more lines you select, the higher the bet will need to be per spin!

5. Check the slot features

The paytable will also have info on the special features of the slot. These vary massively from game to game and it might be a good idea to pick a slot with pretty simple features if you are new to playing at online casinos.

You might find that you prefer slots which focus on a specific feature such as multipliers. There’s a full list below of the types of the slot game features you can expect to find. Things can get pretty complex in some games so take your time and learn the features as you play.

How to play slots at the casino

Before jumping in and playing the nearest online slot game, it’s a good idea to get familiar with the types of symbols and features you’ll encounter.

As the casino industry has evolved online, the way slot games behave has changed far beyond the good old one-armed bandit machine.

Knowing your Scatter from your Wild will help you to get much more out of playing slot games online for real money.

Slot symbols like low-value sumbols and high-value symbols

Slot symbols

Symbols are the basis of all slot games. They appear on the reels and rows, creating winning combinations to reward players for their spins. Slot game symbols often fit with the theme and feel of a game and help to bring it to life.

Low-value symbols

Looking at the paytable will show which are the low-value symbols in any video slot. They are usually ranked in order of value. The royal suit symbols of A, K, Q, J, 10 and 9 are often used as low-value symbols in many games.

High value symbols

These symbols are the ones you want to land as they are worth a lot more when combined on a spin. They could be pretty much anything which depicts characters or features from that specific slot theme.

Scatter symbols

Scatters are sometimes referred to as bonus symbols. Their main use is to trigger special feature in a slot game such as a Free Spins game or similar. It’s pretty rare for scatters to be substituted by wilds in a game.

Wild symbols

Wilds are one of the most popular special symbols around and are a mainstay of the majority of slot games. They can come in several different flavours which act in various ways to mix up the gameplay.

Regular Wilds

This symbol stands in for any other symbol once it appears. Other special symbols like Scatters might not be affected by a Wild. They can have their own value assigned or can assume the value of the symbol they are substituting for.

Reel covering Wilds

These stacks of Wild symbols can be very good news for a lucky player as having a reel filled with Wilds will increase the likelihood of hitting a decent win.

Expanding Wilds

Unlike the Wilds that cover a whole reel, Expanding Wilds will land as a single symbol but will grow to cover more reel spaces once the spin is complete.

Moving/Wandering Wilds

Once a spin is complete, a Wandering Wild will shift position in a certain way, as outlined in the game’s paytable.

Sticky Wilds
The polar opposite of their cousins the Wandering Wild, Sticky Wilds just want to stay put. These Wilds will remain locked in place for a specified number of spins or until a feature is complete.

Expanding reels and symbols

Expanding reels mean that an extra reel or reels are added on via a bonus feature. This expands the number of reels which are shown in the slot base game.

Adding one or more reels will increase the number of symbol spaces and often impacts the number of ways to win.

Colossal symbols

Colossal symbols, as the name suggests, are massive and they can take a game to the next level by covering several symbol spaces at once. In some slot games, they can take over half of the screen and land some almighty wins for the player.

Free Spins Feature

Pretty much does what it says on the tin, these are bonus rounds that do not cost the player anything to play. Free Spins features are triggered when certain symbols appear together, typically scatters.

The amount of scatters landed to trigger the feature can determine how many free spins a player gets rewarded. Although sometimes a random amount of free spins are given to the player.

Re-spin feature

Players sometimes confuse re-spins and free spins. Re-spins are simply a ‘second chance spin’ which can occur in a base game or special feature where the reels are respun without costing anything.

Bonus game

Certain slots offer bonus games as built-in ‘mini-games’ that add to the gambling experience. Most, if not all, bonus games have no skill element and are as random as the main slot game.

Types of bonus games

There are no set rules for what a bonus game should and should not be but there are a few popular formats around.

  • The ‘pick and click’ bonus game presents the player with a number of things to choose from, each containing a prize. Prizes can include coin wins, bonus feature activation, multipliers or free spins. The player chooses the chest, bauble, seashell or whatever it is and receives the prize.
  • The bonus wheel is also a popular choice. This is simply a wheel covered in prizes that the player spins. Whichever prize the wheel lands on is awarded to the player.


Some games include multiplier features which will multiply a win by 2, 3, 4 or more times. They can either be triggered via certain symbols, accumulated over several spins or awarded as part of a bonus feature.

Nudge feature

This feature comes in handy when a player narrowly misses landing a desirable combination. A nudge will knock one reel or more one space up or down, giving you a chance to beat a near-miss situation.

Gamble feature

When you land a win, some slots will offer a Gamble feature, which you can accept or reject. If you take the gamble, the feature offers one of two outcomes – losing the win entirely or doubling it.

The feature usually takes the shape of a guessing game, whereby you bet your win on the result of a random event such as the next card drawn from a deck. The Gamble feature can add thrills if you enjoy a little extra risk in your play.


A Jackpot is a top prize that a slot game offers. Jackpot slots can come in many formats but the only constant feature is the jackpot prize on offer. Jackpots can be local, network, fixed or progressive.

Local Jackpots

This jackpot builds up from players at a specific online casino only and isn’t linked to any other casino sites.

Network Jackpots

This jackpot also called a pooled jackpot, is made up from the bets of all players across all online casinos that host that slot game. Think of it like a lottery where everyone contributes to the total prize fund wherever they are playing from.

Fixed Jackpots

As the name suggests, this jackpot offers a fixed prize amount which does not grow with the number of bets. The fixed prize fund is specific to that game and isn’t part of a network either.

Progressive Jackpots

Games such as Mega Moolah hit the headlines by creating instant millionaires from a single spin. This is possible as all bets placed, regardless of casino or location, contribute to the jackpot’s total.

This can often build into the multi-millions and keeps growing until one lucky player scoops it. These mega payouts only happen every few months but are truly life-changing when they occur.


Since February 2021, Autoplay features are no longer available at UK casinos. This GC-licensing requirements helps you to keep in control of your budget. For more information on playing responsibly, visit our responsible gambling guide.

How to play slots and win

Playing slots for fun is one thing but serious players are always looking to find their next big online slot win. Rather than just randomly hitting the spin button and hoping for the best, there are a few simple strategies that you can use to level up your slot play.

Follow these online slot tips to massively improve the chances of a win.

How to play slots and win

Find the best casino offers

Just taking a quick look around you can see that there’s a massive choice of online casinos out there. The number of casinos is growing daily and so are the range of welcome offers and bonuses on offer.

Competition amongst online casinos for your time and money means they are offering up more than ever to tempt in new players. From free spins to bonus cash, the rewards for signing up can be pretty generous.

That said, always check the terms of any bonuses to ensure that they are worth taking on. Heavy wagering requirements or cash out limitations can quickly make some offers less enticing than they first appear.

Know your slot stats

The difference between a novice and a pro online casino player is how much attention they pay to the stats of an individual slot. Most online casinos will display statistics like RTP and volatility alongside each slot title.

Read up on what these terms mean below and this will help you to seek out the best online slots and forget the rest. If you’ve been playing any game for some time and it’s not paying out then it’s best to step away. Pumping in more funds does not mean that the game owes you anything and will produce a big payout.

Play for free/fun

Many online casinos offer the option to play their video slots for fun rather than real money. This gives players the chance to see what a specific game is all about and test it out fully before putting in any of their own funds.

Return to Player value


RTP stands for Return to Player and is always displayed as a percentage. It indicates to you how much of your bankroll you are likely to win back from a specific casino game over time.

Any RTP percentage given is the result of a calculation based on the result of thousands, if not millions of spins on a specific game. It’s not intended to be any kind of guarantee of what you can win back from a game, only an idea of the amount you can expect to gain back over time.

As an example, in a game with 96% RTP, which might be called the best RTP, the casino will likely receive 4% of player wagers through this particular game. This is often known as ‘house edge’. There are no games around with 100% RTP otherwise casinos would quickly go out of business.

Given this, you might wonder why it’s worth playing slot games. With the outcome of each spin being as random as possible and the RTP only an indicator ‘over time’, the wins or losses each individual player gets from a slot game can vary massively.

The best volatility slots


Volatility, also known as variance, describes the estimated size of your wins and how frequently they occur. It refers to the overall frequency and size of payouts you can expect from a specific slot game.

Slot games are usually classed as having either low, medium or high volatility. Lower variance slots will pay out smaller amounts on a regular basis making them ideal for casino newbies. Whereas high variance slots will pay out bigger amounts but less often.

Medium variance slots are a happy balance between the two extremes and are the most common type found at online casinos.


Slot games are big business and a number of first-class providers have emerged as creative and competitive game developers. You really are spoilt for choice but having that many options can be daunting if you don’t know where to start.

Our slots guide should prepare you for all the terms, phrases, features and contests this exciting genre can throw at you. Always remember to play for fun and only visit reputable casinos. Enjoy!

+10 Years of Experience
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Online Slot Expert

1578 Articles

Leanna Madden is an expert in online slots, specializing in analyzing game providers and evaluating the quality and variety of slot games. With her extensive knowledge, she guides players to the best slot options, including high RTP slots and those with exciting bonus features. Leanna's insights help players make informed decisions and enjoy rewarding slot experiences at online casinos.

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