How Online Slots Work

Reels & rows

Reels are the most important element of an online slot. They are the vertical parts of the game that spin top to bottom after players have set their stake and pressed play. Each game reel will show a different selection of randomly generated symbols with every spin.

Typically, most modern online slot games will have 5 reels and 3 or 4 rows of symbols, traditional slot machines on the other hand would just have 3 reels and three rows with a single payline running horizontally through the middle row. 

The reels and rows of online slots make up a complex grid forming multiple combinations of symbols, and therefore paylines (more on those later).

As online slots have gotten more intricate over the years developers have pushed the boundaries by introducing more game reels, more symbols, more paylines and therefore more winning combinations. 

Paylines

Without paylines there are no winners! Paylines determine whether or not the symbols that have landed on the reels form a winning combination. 

Back when slot machines were first introduced they only had a single payline, players had to match three symbols along this middle payline to win money. 

Most modern online slots will have anywhere between 10 and 243 paylines, however, there are some slots that offer players up to 117,649 ways to win due to the fact that they can fit up to 7 symbols on a single reel.

Paylines can run in a number of different directions, usually from left to right, diagonally and in various zig zag patterns. The more ways to win a game has, the wilder the paylines can be, meaning symbols don’t always have to line up next to each other in order for players to register a win.

Symbols

Every single slot game will feature a range of different symbols that are unique to that game, each symbol is allocated a set value, with some symbols being worth more than others.

Originally, slot machines used symbols such as horseshoes, diamonds, spades, hearts, and bells. Over time these symbols evolved and fruit symbols were introduced such as cherries, watermelon, oranges, bananas, grapes, lemons and apples.

When online slots became prevalent classic symbols still remained, but online slot developers would begin using iconography from playing cards such as the suits and pips. The suits used are Clubs, Diamonds, Hearts, Spades and the pips are 9, 10, Jack, Queen, King, Ace.

Today, most slots use the aforementioned playing card symbols as low-value symbols in their games, whilst using heavily themed symbols that match the game’s design as high-value ones.

Almost all games also feature two or three special symbols, these are wilds, scatters and bonus symbols. Wild symbols are symbols that will stand in for any symbol (except for scatters) to help form a winning combination. Scatter symbols trigger free spins when a certain number of them land anywhere on the game reels, even outside of a winning payline. Bonus symbols essentially do the same as scatters, but trigger a different bonus feature or a jackpot.

Bet level & coin value

The bet level and coin value are two features that many online slots (in particular older ones) utilise. Both of these adjustable components relate directly to how much players are spending on each and every spin of the reels.

The first thing you must understand is that there’s a distinct difference between coin value and actual cost of each spin, it’s quite easy to jump to the assumption that both are the same. 

Most online slots use coins instead of currency for bets and wins. A winning combination, for example, may pay out 100 coins as opposed to £10. Having a common currency simplifies the overall experience and avoids complications associated with different currencies and denominations around the world.

Some slots allow players to adjust the coin value which in turn will determine your stake per spin and ultimately the total amount you can potentially win. The overall stake can be increased or decreased further by adjusting the bet level.

Similarly, some slots have adjustable paylines meaning players can select the number of active paylines. This is controlled by the ‘Bet Level’, also referred to as the ‘Lines’ bet. The higher the bet level, the higher the number of active paylines and so the higher the stake, but also potential winnings combinations.

For example, if you’re playing a 20 payline slot at bet level 1 with a coin value of 0.01 then you will be playing on one payline at an overall cost of 0.01.

If you were to adjust your bet level to the maximum of 20 (meaning you’re playing along all 20 of the game’s paylines) with the coin value still set at 0.01 then your overall stake would increase to 0.20.

Other slots have non-adjustable paylines (known as ‘fixed payline slots’) but will still have a bet level option. Changing the bet level here will still do the same thing in terms of adjusting your overall stake, however, in this case you’d still have all of the available paylines available to you.

Ultimately, slots that feature both an adjustable bet level and coin value allow you to be more flexible with the amount you stake. You don’t tend to see too many games like this now, as they’re considered to be confusing and can deter new (and experienced) players.  However, they do still exist and remain popular with those who prefer Penny Slots where stakes can be reduced to as little as 1p per spin.

Paytable

The paytable is a screen that can be accessed through each online slot’s game menu. It displays the values of each individual symbol (including scatters, wilds and bonus symbols) that appear in the game, as well as displaying the various directions each and every payline goes in (assuming this is a 10-25 payline slot and not one with hundreds/thousands of paylines).

The paytable will also often display other important information that players should always be aware of, this includes the game’s RTP (return to player), the maximum win potential of the slot and information on each bonus feature and how to trigger it.

Bonus features

Almost all modern online slots come complete with a wide range of bonus features! These are hugely lucrative mini-games that can be triggered by landing a specific set of symbols in a specific order on the reels.

The most common bonus feature found in almost every game is free spins, these are a set of spins that are usually triggered by landing 3 scatter symbols anywhere on the game reels. 

Free spins allow players to accumulate successive wins at absolutely no cost to themselves (other than the initial spin that triggered the free spin bonus). The more scatter symbols players land on the reels (usually between 3 and 5), the more free spins they’ll receive in one go. It’s also possible for players to re-trigger free spins during the bonus.

The more intricate and well designed the game, the more intricate and well designed the free spins bonus will be. Some developers will include bonus modifiers (events that change the way the bonus game plays) during free spins, this means that players can potentially trigger much larger wins. 

These modifiers might be something like sticky wilds (when symbols stay in one place for the duration of the feature), expanding reels (where more symbols can land on a larger single reel) or the promise of additional high-paying symbols landing during free spins.

Other bonus features include pick and click mini-games, in which players are tasked with picking certain items in order to collect win multipliers, wheel-of-fortunes and symbol substitutions just to name a few.

There are no rules that state whether online slots should feature bonuses, however, in this day and age it’s come to be expected that a title will at least offer players free spins, if not something equally as lucrative. Realistically most players will choose to ignore games that don’t have bonus features unless they have huge perks such as a high RTP or have the potential to pay out thousands, if not millions in jackpots.

Jackpots

Some online slots will feature jackpots! These are huge massive sums of money that can be won randomly on any spin of the game (this includes losing spins), or by triggering a specific combination of symbols and then playing a mini-game such as a pick and click bonus or wheel-of-fortune to determine how much is won.

There are several different types of jackpots players can win trigger when playing jackpot slots, firstly we have networked progressive jackpots. These are large jackpots that are spread across multiple online slot sites that continue to grow in size every time a player spins the reels, as a small percentage of their bet goes towards funding the jackpot.

Sometimes a networked jackpot will be spread across multiple games in an online slot series such as Age of the Gods or Kingdoms Rise, or it might be a progressive jackpot that’s spread across a developer’s entire portfolio of slot games such as the Jackpot King, Mega Drop Jackpot or the WowPot!

Progressive jackpots can either be placed into one large pot which tends to pay out once every few months, or it can be spread out across multiple pots, some of which will have certain criteria to meet and will pay out on an hourly, daily or weekly basis, such as Red Tiger’s Daily Jackpot. 

The other kind of jackpot you will often find in online slots are local jackpots, these tend to be smaller jackpots that are linked to just one slot. They’ll either be fixed at a certain amount of money, or they’ll be progressive whereby anyone playing that slot will contribute to the prize fund.