2025-04-11

How do online slots work?

Online slots are some of the most popular games amongst online casino players. They come in a wide variety of themes, offer a selection of different bonus features, and serve up huge jackpots.

In this guide, we’re answering the question of how online slots work, covering the different types of slot games, how you can play them, and what keeps them fair. You’ll also find a collection of the most common terms to help you understand everything there is to know about slot games.

Online slots explained

Online slot games are a modern recreation of the original one-armed bandits that filled casinos of the past. Instead of being mechanical devices that are controlled by moving parts, these digital versions are run by computer software.

The Basics

To start a slot game, you select the amount you want to bet per payline and choose the number of paylines you want to play with. Once satisfied, you hit the spin button and the reels burst into action.

Once they come to a rest, matching sets of symbols on the paylines will result in a payout. The exact size of the payout and how these symbols are matched up will vary from game to game. Once any prizes have been awarded, you can spin again.

Symbols

There are a few different types of slot games, but they all share the same key characteristics. Firstly, they all use a selection of different symbols, and your task is to try to create winning combinations by matching as many of them on the same payline as possible.

The symbols will vary from game to game, matching the slot’s theme. There are some common types that you’re likely to come across frequently, such as:

10, J, Q, K - Matching the values of playing cards, these symbols are often used as lower-value symbols.
Fruit - Fruit symbols are also very common in slot games which is why they are sometimes called “fruit machines”.
BAR - The BAR symbol is another common standard slot symbol and comes from historic slot games.
Themed Symbols - Symbols that are based on the slot’s theme, such as characters, objects, or animals are usually some of the higher-paying standard symbols you’ll see.
Wild - The Wild symbol looks different in every game, but it is used to substitute for any symbol on a payline, helping you to get more wins.
Scatter - The Scatter is similar to the Wild but can make winning combinations without being in the same payline.
Bonus - Bonus symbols vary from game to game, but landing enough of them at once can trigger a bonus feature.

Bonus Features

Most slot games include one or more bonus features. They are all different, which makes playing slot games such a varied and entertaining experience. Some simple bonus games include free spins for the standard reels or getting to spin a prize wheel, others can be more elaborate.

Bonus features and games are triggered by landing certain symbols on the reels and offer you the chance to bag bigger wins.

Random Number Generator

Behind the scenes, a random number generator (RNG) is used to ensure slot games are fair and unbiased. They feed truly random inputs into the game’s code so that the symbols don’t appear in predictable patterns.

As a player, you don’t see the RNG or need to worry about how it works, just know that it’s working in the background so you can play all your favourite slots safe in the knowledge that they’re fair.

Different slot games and what they mean

There are hundreds of different slot games that you can choose from, covering just about every conceivable theme and with a wide range of features. However, there are a few common categories that you’ll come across when you play.

Traditional Slots

Traditional or classic slots are often simpler, using classic symbols like fruit and fewer reels. If you want an authentically retro slot experience, then these are the games to go for.

Themed Slots

Most slot games are themed, with beautifully crafted graphics, engaging characters, enchanting music, sound effects, and exhilarating animations and cut scenes. Here are some of the most common themes you’re likely to come across:

Ancient Egypt - The backdrop of pyramids and sphynxes are hugely popular amongst slot players, so you’ll never be short of Ancient Egyptian slots.
Leprechauns and Irish Folklore - Shamrocks, pots of gold, and friendly little leprechauns are a common sight in slot games.
Fishing - No need to be an angler to reel in some big catches if you’re playing a fishing slot game.
Ancient Greece - The Ancient Greeks are another popular historical source for slot games with many borrowing from the era’s mythology.
Sweets - If you have a sweet tooth, you can get a sugar rush from the sheer number of candied slot games.
Movies and TV shows - Some slot games feature the characters and plot from famous movies and TV shows.
Bands - Just as with film and TV, there’s a long list of legendary musicians that have their own slot games.

Slots With Larger Reels

The first slot games featured three reels with a single payline, but modern video slots typically offer you more than this. Some traditional games stick with three reels, though they may have a handful of paylines to give you more chances to win.

Themed games, on the other hand, may have four, five, or even more reels to give you more variety. Most also have more rows on these reels, showing you more symbols at once and increasing the number of paylines.

Cascading Slots

Cascading slots work a little differently from traditional reel-based games. They show you a grid of symbols that’s very similar to any other slot, however, instead of trying to match symbols on a payline your task is to find groups of adjacent ones. The more that are touching each other, the bigger the payout.

Jackpot Slots

Jackpot slot games offer an additional prize that is much larger than the standard payouts you can unlock. They hit less frequently but offer huge wins.

Some jackpots are described as “progressive” because they slowly grow larger and larger with every spin that you and other players make. The jackpot can payout at any moment too, offering you the chance to win each time you spin.

Megaways

Megaways slots are a popular type of slot that offer tens of thousands of different ways to win with every spin. They do this by varying the number of symbols on each reel with every spin. You can find Megaways versions of many popular slots, so you’ll be sure to find one that you’ll like.

Key terms and what do they mean?

As you play slot games, you’ll come across a lot of different words and phrases. Here’s a handy guide to what they mean.

Symbols - The different icons that you must match to win.
Reels - The spinning columns that contain the game’s symbols.
Rows - The lines across the reels.
Paylines - The different lines that you can match symbols to win.
RTP - RTP is an acronym for “return to player” and is used to express the theoretical percentage of your bets you can expect to receive back when you play that slot.
Volatility - This is a measure of the size and frequency of wins from a slot game. Low volatility slots have more frequent wins that are smaller, while high volatility slots payout less frequently but do so with larger amounts.
Payout - The amount you receive for each win.
Jackpot - A large prize offered by some slot games.
Megaways - A special mechanism on some slot games to increase the number of slot games.
Multiplier - A slot win that pays out a multiple of your original bet.
Wild - A special symbol that can substitute for any other, helping you to make more winning lines.
Scatter - Another special symbol that can payout without the symbols being on a payline.
Free Spins - Opportunities to spin the reels for free.
Bonus - Bonus features give you chances to win more by using different mechanics from the standard base game.
Spin - The action of setting the reels in motion.
Auto Spin - Most slots have an auto spin feature that lets you keep spinning the reels without having to click each time.