The Mechanics of a Slot Machine: How It Works

Log on to any online casino and the odds are you're going to see hundreds and hundreds of slot machines. 3 reel. 5 reel. Cascading. Megaways. Progressive. These slots are a stable of any online casino. But how exactly do they work? Today, we are going to take a closer look at how this slots actually work so players will have a better understanding of how their favorite games work the next time they sit down to spin. Let's dive in!

First off, the basics

Ask any contractor and they'll tell you that to build a good house, the first thing you need is a foundation. Well, the foundation of slot machines are the reels, symbols and paylines. They need each other to be able to give players the exciting gameplay they're accustomed to.

  • Reels

Reels are the vertical columns that spin a slot's set of symbols. These reels can come in a variety of different numbers as well: 3 reel, 5 reel, 10 reel and so on.

  • Symbols

Symbols are the icons players will see filling up the reels of a slot. These vary and are usually tied into its slot's theme. Players can see themes ranging from fruit to space to ancient Rome to Greek Gods. The options are endless and it's always fun to search around different slots and play a variety of themes.

Each symbol will hold a specific coin value, with non-premiums - typically the cards 10, Jack, Queen, King, Ace - holding the lowest values. The premium symbols - those characters or other fun themed-symbols - will hold the higher values.

Wild symbols will substitute for most symbols, giving players for chances to win, while Scatter symbols are typically reserved for games that give players the opportunity to spin into bonus features.

  • Paylines

Paylines are how players spin into winning combinations. The old school 'one armed bandits' had one payline, but with the boom of online slots, players can now enjoy more chances to win with 25, 50, 250 or even 1000 different paylines.

Random Number Generators

Online Slots Now that we have the basics down, how exactly do these slots pay out? Well, that's where random number generators - or RNG - come into play. RNGs are algorithms created by people much smarter than this author that basically generate an infinite sequence of numbers in a random order.

Why is that a big deal? Well, think of RNG's like snowflakes. No two snowflakes are alike. The same basic concept can be used with RNGs. Their algorithms guarantee that every spin is different from a previous spin. This gives players the knowledge that the slots they're playing are fair and there's nothing predicting the outcome of their spins. It's all random.

Return to Player

Any player would love to know what the potential for payouts are on any given slot. That's where Return to Player - or RTP - comes in. This information gives the player an idea of the percentage of their money they can expect to win back over a period of time. So let's say a slot has a 95% RTP. That means that on average, a player can expect to receive 95% of their wagered money back. It's important players know that this means over a long period of time. Do not go into a session and except to win back 95% of your money. You could be in for a rude awakening. Every session will be different, meaning players could hit big or loose big. RTP is just the average of the spins over a long period of time.


Ever wonder what those lightning bolts are that you see when you first click on a slot? Those represent that specific slot's volatility. It's basically the risk factor that is associated with that specific slot.

A slot with a low volatility - represented with a low number of lightning bolts - means that players can expect that slot to pay out more frequently but the wins will be on the lower end. A slot with a high volatility - more lightning bolts - means players can expect larger wins but at a much less frequency.

Now, that's not to say a slot with a low volatility will never pay out a big win. It just mean that on average, slots with low volatility will pay more frequently but with smaller wins. It's alway important players check a slot's volatility before playing. This information will help them determine how much to risk and what kind of wins they can expect.

Bonus, Bonus, Bonus

The best thing about online slots is that they have the ability to incorporate bonus features like free spins, multipliers, bonus games, and other fun features. Players will typically spin into these features by spinning into 3, 4 or 5 SCATTER symbols - or is a game has an extra bonus feature then 3, 4 or 5 BONUS symbols.

Slots that incorporate these features give players more chances to hit it big and add to the overall enjoyment of a game.


Computer programming, artistry and math. Those are the basic components that make up your favorite online slot machines. Players never really put much thought into what goes into these games - this author is certainly guilty of that - but by familiarizing yourself with the nuts and bolts of these amazing games, you're more likely to enjoy your sessions even more than you already do.

So the next time you sit down and spin, take a second to marvel at the end product, but don't forget everything that went into making that slot what it is!