Slots are by far the most popular kind of casino game which is why you’ll find more slots than other game type at most land, online or mobile casinos. At bigger online and land casinos, slots can number in the thousands and include a wide variety of variants such as classic slots, video slots, bonus slots and progressive slots.
The name comes from the coin slot on the original slot machines, also known as ‘fruit machines’ because of their symbols depicting various fruit, and ‘one arm bandits’ because of the machine’s single pull arm and propensity to ‘relieve’ players of their money. At online casinos they’re simply called slots or slot games.
In the late 1800s Charles Fey of San Francisco built the world’s first slot machine called the Liberty Bell (after one of its symbols), which had 3 reels (with 5 symbols on each) and one pay line. Three Liberty Bells across the pay line yielded the game’s biggest payout of 50c (10 nickels), which was a respectable sum back then.
So successful was the game that it spawned an entire slot machine industry that eventually moved from the United States to many other parts of the world. Today land and online slots turnover billions of pounds globally, and continue to be the casino gambling game of choice for new and seasoned gamblers alike.
On this page you’ll find everything you need to know about the types of slot games. We’ll also show you how to play slots optimally and improve your chances of winning larger amounts more consistently.
Slots Explained
In their simplest form, slots are coin / card or credit operated machines or virtual games with 3 or 5 reels that are populated with a variety of symbols, with one or more pay lines. The idea is that for a specified bet you get to spin the reels.
If the reels stop and the symbols under an active pay line (or lines) form a winning combination (as per the respective slot game pay table), you’ll be paid out according to your respective bet size and any games features that have been activated.
Slot come in a wide variety of themes and variations, complete with bold, bright and colourful displays, background music and sound effects, and in some cases, 3D style animations and storylines. The sky is the limit when it comes to online slot design which is why there are so many to choose from at top UK online slots casinos.
Types of Slots
There are various kinds of slots, but the four most common are:
- Classic Slots – Old school slots with 3 reels and 1 pay line.
- Video Slots – Modern 5 reels slots with multiple pay lines.
- Bonus Slots – Slots that have multiple bonus rounds or games.
- Progressive Slots – Slots with an ever-growing jackpot linked via a network.
How popular an online slot game turns out to be dependant on a host of factors like:
- How attractive and engaging its theme, graphics and sounds are.
- The range of coin or denomination sizes it accepts to suit any budget.
- How many features it has such as Wilds, Stacked Wilds, Expanding Wilds, Sticky Wilds, Scatters, Free Spins, Bonus symbols and rounds, Multipliers and Gamble.
- How often it pays out i.e. whether it’s ‘loose’ (pays out smaller amounts more often) or ‘tight’ (pays out bigger amounts less often).
- How generous its payouts and/or progressive jackpots are.
- How high its payout percentage (return to player) is.
- Which firm developed it i.e. some online casino game developers are better than others.
- Whether it’s browser-based (which means you can play it on any computer or smart mobile device), or solely downloadable, where it has to be installed and can only be played on certain platforms (like Windows-based computers, for instance).
How To Play
Slots are the easiest of all casino gambling games to play, particularly online slots. All you need to do is take a minute to sign up for a real money account at any of our UK casinos online, deposit some funds easily and instantly into your account before heading over to the games lobby to pick and click to open any slots game you want.
Read on to find out what you have to do next:
Choose a Bet Amount
Except for a handful of progressive jackpot games, most online slot games allow you to choose a denomination or coin size to match your budget. This is great because it means you can enjoy the latest real money slot games regardless of if you have a small, medium or large amount of playing funds.
To find a slot game that suits your budget, look at its minimum bet. If you can afford the minimum bet, you can afford to play the game. That said, try and find slots that you can afford to play on the maximum bet. That way you’ll maximise your winnings and chance to win the progressive, if applicable.
Always check the coin size before your first spin because some online casinos default the coin size to the maximum, and a spin at that level could seriously eat away your playing funds. Once you’ve selected a coin size that fits your budget and will give you a lengthy amount of playing time, hit the Spin button.
Slot Pay Lines
The pay line or lines is key in any slots game because only symbols that fall under / follow a pay line will pay out. In other words, no pay line no pay. Typically, the more pay lines a slot has, the higher the cost of a bet.
For instance, a minimum bet of 10p in a game with 25 pay lines will cost you £2.50. Although you don’t have to select all the pay lines, you should always select all pay lines, even if it means choosing a smaller coin size.
In that way you’ll give yourself the biggest chance of hitting a winning combination. Depending on the particular slot game, pay lines pay from left to right (which is typical), some from right to left, and some both.

Slot Features – Wilds, Scatters, Free Spins and More
Slots would get boring very quickly if it wasn’t for the variety of features that most offer. These are add-ons in effect that either help make winning combinations or grow your winnings when you land them.
Below is a brief explanation of the most common slot features you’ll find in most popular online and mobile slot games. They are split into two types of features: internal slot features and external slot features.
Internal Slot Features
These are features that you’ll encounter during actual game play, and are controlled by the game:
Wilds (regular)
Symbols that substitute for any other symbol (with the exception of Scatters, Free Spins or Bonus symbols) to help make winning combinations as per the payout table.
Stacked Wilds
Wild symbols that cover an entire reel to make potentially even more winning combos.
Expanding Wilds
Wilds symbols that turn an entire reel wild, essentially becoming Stacked Wilds.
Sticky Wilds
Wild symbols that stay put or ‘stick’ in place over multiple spins, which means their benefit lasts for more than just one spin.
Scatters
Symbols that offer small payouts in their own right and also trigger bonus features, typically when 3 or more appear anywhere on your reels. (Note: Scatters don’t have to appear in pay lines to pay). [[[Scatters usually multiple wins and trigger bonus rounds and free spins.]]]
Bonus symbols
Getting these in a specific sequence or reels can trigger or activate a special bonus game or round. Bonus games vary from slot to slot, although most entail you choosing a certain number of objects to reveal their hidden cash amounts. These are sometimes also scatter symbols.
Free Spins
Get three or more Free Spins symbols and you’ll trigger a set amount of Free Spins, where the reels spin automatically and pay you any winnings accrued without you having to bet first.
Multipliers
These multiply your winnings by a specified amount, such as x2, x3, x4, x5 and so forth.
Gamble
This feature only comes into play just after you’ve racked up a winning combination, where you’re offered the chance to double your winnings (or lose it all) by way of some type of ‘coin flip’ challenge.
External Game Slot Features
These are features that are external to the actual game play and you can control them all:
Coin Size
You can pick a coin denomination from the range on offer.
Pay Lines
You can select one or more pay lines to play. (Your total bet size is worked out by multiplying your chosen coin size by the number of pay lines. For instance, 1p x 25 lines = 25p per spin).
Turbo Mode
By selecting this, the slot reels spin and stop even faster to reduce the time between spins if you’re in a hurry to win big.
Auto Play
By selecting this, the game plays your chosen bet automatically a set number of times, only stopping if you hit a big feature that requires you to interact with it.
Sound On / Off
Unlike land casino slot machines, most online slot games allow you two turn off the background music and/or sound effects if they get too loud or annoying.
Slot Payout Tables
Before you play any slot game, you should always check out its payout table first to see what its highest-paying combinations are.
In that way you can make an informed decision as to whether the coin size you’re prepared to play with is actually worth the potential payouts or not.
Also, by first looking through slot payout tables, you’ll know exactly what winning combinations to chase, which makes for greater excitement and enjoyment.
Slots Payout Percentages
Also known as return to player (RTP), a payout percentage is the overall average of how much of a pound wagered in a particular slot game is paid out as winnings.
For example, a video slot with a payout percentage or RTP of 87% means that over time 87p of every pound wagered or spent on the game is paid out as winnings, while the remaining 13p is retained by the casino.
To get the most out of every online slots session, you should only ever play slots with the highest payout percentages. While a slot game with a high RTP won’t guarantee you always log off with a pile of cash, it does means you’ll get ‘more bang for your gambling buck’ during winning streaks.
Here are ten slots with the highest RTP percentages and where you can play them:
Game | RTP% | Where to Play |
---|---|---|
Goblin’s Cave (Playtech) | 99.1% | Play at Mr Green Casinoread review |
Nemo’s Voyage (WMS) | 99% | Play at William Hill Casino read review |
Mega Joker (Netent) | 98.9% | Play at Energy Casino read review |
Alaxe in Zombieland (MGS) | 98.86% | Play at Betway Casino read review |
Monopoly (IGT) | 98.14% | Play at Mr Green Casino read review |
Good Girl Bad Girl (Betsoft) | 97.8% | Play at Videoslots Casino read review |
Kings of Chicago (Netent) | 97.8% | Play at Hello Casino read review |
Blood Suckers (Netent) | 97.6% | Play at Hello Casino read review |
Devil’s Delight (Netent) | 97.6% | Play at Mr Green Casino read review |
Retro Reel – Extreme Heat (MGS) | 97.5% | Play at Roxy Palace Casino read review |