Online Slots Guide – Slot Machines Explained

Martin Singh
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Online slots have become some of the most popular games at today’s online casinos. And while players still love games like blackjack, video poker, and roulette, online slots remain some of the most commonly played games. Besides, online slots are the category with the widest variety of games at any online casino. 

The rules of playing slots are the same—whether playing in a land-based casino or an online casino. A player places a wager and then spins a set of reels. Now, the reels stop at an unsystematic position, and you only when the reels stop, and they have the same symbols. When it comes to online slots, the rarer the winning symbols, the higher the amount a player can win. The amount a player can win in every combination is well-defined in the paytable.

How Online Slot Machines Work

The Random Number Generator (RNG) is the driving force behind today’s slot machines. This technology, which is used on physical and online slots, ensures that every spin is independent of all others. Once you activate the slot machine, the RNG starts to generate numbers—this happens at a rate of 100s or 1,000s per second. 

When you make your wager and press the spin button, the machine takes the recent batch of numbers to determine the symbols displayed on the reels. That means the spinning reels will give you a visual indication of the digits selected by the RNG. As soon as you push the button, the machine determines the outcome faster than your brain can process. 

At times, some symbols on an online slot machine will appear more repeatedly than others, which means that the game is ‘weighted.’ This is very common in online slots—if that wasn’t the case, major symbols would appear more repeatedly, and the online casino could end up losing a lot of money in the long run. 

Here is how an online slot machine works whenever you place a bet:

  1. A Random Number Generator (RNG) generates a random number
  2. The slot’s mathematical unit takes that random number and determines where the reels should stop
  3. The slot’s reels stop at the determined position and calculate the result of the spin
  4. The machine displays the result of the spin

Please note that your loss or win in every spin isn’t pre-determined or predictable, but it depends on your luck. So, you cannot rely on your previous losses or wins or other players’ losses or wins to determine the outcome of a spin.

Online slot machines are programmed with a predetermined payback percentage. Typically, this is the amount to be paid back over the lifetime of the slot machine. So, a slot machine with an 85% payback is expected to deliver 85 cents for every dollar wagered. However, it’s important to note that the payback amount can fluctuate significantly in the short term. 

Online Slots RTP and Variance/Volatility

Return to Player (RTP) and volatility are the two most critical mathematical characteristics in any slot game. These two influence how often and how much you win. Now, let’s look at these two characteristics in detail. 

Return to Player

Also known as payout percentage or payout ratio, RTP is a long-term arithmetic rate of the money won divided by the money wagered. Here is a simple explanation to help you understand how an RTP works;

If a slot has an RTP of 96%, it means that if a player starts playing with $100 and then plays 100 rounds at $1 per round, they should end up with approximately $96. Now, If you want to play a few rounds, your current RTP might vary from 30% – 1,000%. However, the more you play, the higher the chances of hitting the statistical RTP of the game. With that said, it’s important to note that the average RTP of slot games ranges from 90% – 95%, but you can find some slots with an RTP of 98%. 

The RTP is a common feature in online slots because it can be displayed as a single number. This makes it easy to compare, as most leading online gaming providers usually declare the RTP of the games they provide. So, players can use RTP for very simple calculations, like how much money they can lose from a bonus if they choose to roll it over. 


Now, since we’ve understood what an RTP is, let’s look at what slots volatility is all about. Please note that the volatility of online slots is very complicated. That’s why we’ll start by explaining the volatility of roulette:

  • If you bet on a color, you can win 2x your wager. Also, you have higher chances of winning on every bet you place (you can win 18 out of 37 rounds).
  • If you bet on a number, you can win 36x your bet, but your chances of winning are slim (you can only win once every 37 rounds).

As you can see, roulette volatility is expressed in numbers—from 2 – 36, but this depends on the stake you choose. A higher volatility means you can win a higher amount. However, the frequency of winning is very low, and there’s a high chance for you to lose your money faster. 

On the other hand, the volatility of slot games cannot be expressed, as a player can win thousands of different amounts because of the endless available winning combinations. And, because slots volatility cannot be expressed as one number, gaming providers classify slots into these three volatility categories:

  • Low 
  • Medium
  • High

Please note that these three categories cannot be compared or applied in any calculations. However, they can give a player an idea about the volatility of a slot game they are about to play. With that said, players need to note that the volatility of online slots can be estimated from the reel set and paytable. Thus, you should always go for slots with the highest winning combo. Besides, you need to know the chances of hitting the right combination and how much you’d win if you got the combination right. 

Generally, high-volatility slot games give players a chance to win lucrative amounts, but you can lose a lot of money in the process. Lower stakes, on the other hand, allow players to win less and have lower chances of losing a lot of money. 

Unlike lotteries, online slots are the most volatile casino games you can ever play. In fact, the volatility of slot games is higher than the RTP of popular games like roulette and blackjack. For instance, the average RTP of lotteries is about 50%, but what motivates people to continue playing lotteries is the chances of hitting the life-changing jackpot. 

Tips to boost the volatility of a slot machine

These are the tricks that you can use if you want to increase the volatility of online slots:

  • You can use the double-up button – this ensures that the RTP remains the same while increasing the game’s volatility to the desired values by placing bets until you win a significant amount. 
  • Play slots with a single payline and increase the wagers per line – while the chances of winning in such a payline are lower, you have a chance of winning a higher amount. 

Types of Online Slots

One notable thing with online slots is that you can find a wider variety than in land-based casinos. And each slot has its unique characteristics—like special and regular symbols, a paytable, and bonus games. Certain online slots go together with lucrative progressive jackpots. In contrast, others allow players to enjoy a wide variety of special features, like multipliers and bonus spins, which are awarded if a player succeeds in hitting a specific symbol combination on the reels. 

The realistic sound effects, graphics, and animations add additional value to the thrill of online slots. Moreover, we cannot underestimate the convenience and flexibility of playing online slots. With that said, it’s important to note that there are numerous types of online slots, which we shall discuss in detail below. 

Classic Slots

If you prefer simplicity over fanciness, you should try classic online slots. These slots resemble the original slot machines that were introduced to physical casinos. A classic online slot has three reels and a single horizontal payline that spreads across the reels. However, you can find some 3-reel online slots with more than three paylines. For example, the Break Da Bank classic online slot provided by Microgaming has three reels with five paylines. On the other hand, Playtech’s online slot, Chinese Kitchen, presents players with three reels with eight paylines. 

Typically, classic slots feature fruits like oranges, cherries, and lemons as the symbols on the reels. Also, you might find other symbols like lucky sevens, bars, or bells on classic online slots. However, you should note that classic online slots are very simplified and lack extra features. But you can still find some three reel slots that provide bonus games and scatter and wild symbols on rare occasions. 

The simplified design of classic slots is very beneficial for newbies. However, it’s important to note that classic slots have a limited number of betting options and are ideal for players with limited budgets. Moreover, the betting range on 3-reel online slots is restricted to a maximum of three different coin values. 

5-reel Slots

5-reel online slots are some of the most popular types of online slots. They resemble 3-reel classic slots, but they have an additional two reels. The additional rows allow players to hit the additional available paylines. 5-reel online slots come with bonuses, mini-games, and engaging and exciting themes. And, since the matrix is larger, 5-reel slots offer a wider selection of features and symbols. 

Some of the most advanced 5-reel slots have a higher number of paylines, which allows players to hit more winning combinations and boost their profitability. At times, advanced 5-reel slots have more than 100 paylines, although most titles have between 10 and 50 paylines. These lines can run diagonally, horizontally, on V-shapes, or zig-zag across the reels. 

In most cases, the paylines on 5-reel slots are adjustable, allowing players to choose the lines they want to activate and wager on. However, if a winning combination lands on a deactivated line, this doesn’t count as a win, and the slot doesn’t pay out. Other 5-reel slots have fixed numbers on the payline, meaning you cannot choose the lines you wish to bet on. Rather, you are required to wager on every line per spin. 

Because 5-reel slots have two extra reels, multiple paylines, more symbols, and additional special features, their paytables have more detailed information. Thus, players are encouraged to check the paytables before playing to understand the payouts of the slots. 

Progressive Jackpots

Also known as progressive slots, progressive jackpots are some of the most lucrative online types of online slots. These slots provide players with the opportunity to win millions instantly. The main attraction of progressive slots is the ever-increasing jackpots on offer, which continue to increase as more and more players place their wagers. So, if you haven’t tried progressive jackpots, there’s a chance you are missing out!

Progressive slots work differently than normal online slots, as they have growing jackpots. When you place a bet, a certain portion of your money goes to the ultimate prize pool, increasing the jackpot’s value. Now, the more the number of players participating in that jackpot, the higher the prize pool, which can be millions of dollars. 

Some progressive jackpot online slots are operated over a wider network. That means the gaming provider hosts the jackpot across numerous online casinos with the same prize. As a result, these jackpots have the highest payouts, especially if they have been building for a long time. And, once a player wins the mega jackpot, the prize disappears, and the game defaults to the original minimum prize and starts building again. 

Please note that progressive jackpots are not similar to online jackpot slots. Generally, jackpot slots have a fixed and predetermined jackpot waiting for players to hit the winning combo on the reels. On the other hand, progressive jackpots build with every wager made, meaning the ultimate prize continues to grow until a player hits the right combination. Thus, progressive jackpot slots can reach unimaginable levels if the prize isn’t claimed. Moreover, the more accessible the progressive slot is the higher prize. And, a progressive slot that hasn’t been claimed for a long time attracts the attention of many players. However, it’s not common for progressive jackpot slots to grow faster if more players get the attention of the slot. 

Virtual Reality (VR) Slots

Today, we are in the age of VR, and many industries have embraced this technology, including the online gambling and betting industry. As a result, more and more online casinos are now offering virtual games and experiences; thanks to VR—you only need to wear a special VR helmet to immerse yourself in this thrilling experience. 

Virtual reality online slots allow online casino enthusiasts to enjoy a virtual environment with a realistic gaming experience that resembles an actual casino. The isolated and soundproofed VR cases have several LED displays and a quality sound system. The VR game room sometimes has several slot machines for players to choose from. 

Interactive Slots

Also known as I-Slots, interactive online slots have proved to be a key development in the gambling industry. The multi-reels and multi-paylines are a bit different than what you’d see in other online slots. These slots rely on modern computers’ features to allow players to create their own storylines. Thus, players can either participate in a game-advancing slot or play different reel combinations when creating their own storyline. 

When playing i-slots, you will realize that they build to become entertaining online games. If you are used to playing online video games, you’ll realize that interactive slots are very easy to learn. In addition to the conventional component of reel slots, certain games in interactive slots trigger bonus stages, which allow players to participate in mini-games. These games give players a better chance of winning. However, you need to note that interactive slots don’t depend on luck like traditional slots—rather, players with the highest skills have a better chance of making a profit. 

Common Features of Online Slots

Now, since you understand the different types of online slot machines, what makes a great one? By understanding the features you should look out for, it becomes easier for players to increase their chances of winning in the long run. This section will explore the most important things to consider before choosing an online slot machine. 

So, what should you look for?


Most people love playing online slots because of the wide variety of themes they enjoy. Online slots come with various themes, including fantasy, action, films, TV series, and adventure. Also, we cannot forget fruit-themed online slots, as this is the theme for classic slots. In addition, we have a wide variety of other themes for online slots that have become a standard in the industry. Some of these themes include movie and band-themed slots, Egyptian-themed slots, horror-themed slots, music-themed slots, and oriental-themed slots, among others. Interestingly, online gaming providers continue to release more themes for online slots daily. 

The thing is, whatever your hobbies or interests are, it’s highly likely that you will find an online slot with a theme that suits them. And, you will never get bored—gaming providers are dedicated to keeping you updated with the latest and interesting themes so that you can always find something new whenever you log in to your favorite online casino. 


Another common feature that you will find in almost all online slot machines is wild symbols. Now, depending on the slot game’s theme, you can choose the effect that will appear when it comes to the wild cards available. 

The total number of winning players ultimately depends on the available wild cards in your payline. That’s why a player should review the payline in detail before making the final decision. With that said, it’s important to note that different online slot machines have a different number of wild cards. 


Typically, every online slot machine has a scatter symbol. Today, it has become mandatory for every slot machine to have a scatter symbol. For some machines, it’s possible to replace the scatter symbol with the bonus symbol since both have the same meaning. The primary objective of scatter symbols is that players can use them to trigger different bonus games. Now, the game you choose will determine the bonus amount the scatter symbol will provide. 

Other Special Symbols

If you are new to playing online slots, you will realize that the symbols of any game keep on changing with time. Thus, as time passes, you will notice other symbols being added to your favorite online slot games. The most common symbols you will come across include stacked, sticky, expanding, and exploding symbols. Please note that these symbols make players more interested in playing online slot games. 

Ways of Winning

To have a better understanding of online slots, you can make a comparison between modern slot machines and classic ones. Typically, older slot machines had single paylines. However, this is not the case with today’s online slot machines, which have numerous paylines. 

If you use such features well, you will increase your chance of winning whenever you play an online slot game. Moreover, you can opt to consult an expert in online slot games if you want to get tips on how to better your chances of winning whenever you play online slots. 

Free Spins Rounds

Free spins are very common on most online slot machines. Moreover, they are a beneficial feature that offers players a certain number of free spins to increase the amount they can win. Various methods are used to generate free spin rounds, like when a definite cipher lines up on the reels. However, the number of spins you get will depend on the type of game you choose. Moreover, your rewards will start to measure up as your spins turn around the reels.

These are the common features that online slot machines provide to players. However, it’s important to understand that the features have variations depending on the slots that you choose. Therefore, a person needs to take time and analyze the slot machine they are interested in and choose one with features that boost the chances of a player winning. 

How to Play Online Slots and Win

Playing online slots is very different from other online casino games like poker or blackjack since it doesn’t require the same instincts or strategy. However, you must have a general understanding of how online slots work and your odds from one machine to another—doing so betters your chances of winning. While there are numerous myths about the strategies you need to play online slots, here is factual advice to help you play and win online slots. 

Online Slot Spins Are Random

This is an important point you should consider before playing slots. Legitimate slots, whether in land-based casinos or online, are random. That means every spin is independent of the previous one. And while you might come across some strategies claiming otherwise, always remember that spins on legal and regulated online slots are random. 

Now, this reality is very critical when it comes to understanding how to play online slots. This is because it’s very hard to predict future results depending on past results. Most players in online casinos believe that if they lose several spins in a row, they will win very soon. However, you should never attempt to play slots with this notion, as you will end up disappointed. If you know that every spin is independent, you should know there is no way to predict the following spin. That means playing and winning online slots is 100% luck. 

Have Personal Limits

In addition to knowing the randomness of online slots, you also need to play wisely if you want to be successful. That means you must have personal limits and self-control.  

For instance, you might need to set a daily, weekly, or monthly loss limit whenever you play slots. The limit is a bankroll that you wouldn’t mind losing; once you lose it, you cannot play further. Also, you might need to set a win limit to help you walk away with some profits rather than continuing to push for more winnings. Ultimately, setting personal limits when playing online slots can help you take advantage of your wins and mitigate losses. 

Choose the Right Slot

If you want to be successful when playing online slots, you must learn to control whatever you can. As indicated earlier, all the spins are random—meaning you cannot predict or control results. However, you can choose the slot you’d like to play and set loss and win limits. 

So, how do you choose the right slot?

  • Go for slots with a higher Return to Player (RTP) – the RTP of online slots differ from one machine to another. That’s why you should aim for slots with a higher RTP, as this increases your chances of winning more. Most online slots have a Return to Player of between 90% and 95%. However, certain slots have an RTP of 98%, but they are very rare. 
  • Choose a variance that matches your goals – the variance of slots determines the odds of winning whenever you start a spin. Slot games with a low variance put you in a better position to win, but you won’t win a significant amount. On the other hand, slot machines with a higher variance mean you are less likely to win, but if you do, you can win higher amounts. So, if you are searching for higher jackpots, choose slots with high variance. And, if you want to win more frequently, go for slots with low variance. 

Make sure you understand the rules and features of the slot you want to play – most of today’s slots have a bonus round and features that give players additional ways of making money while playing slots. For instance, most progressive slots don’t allow players with minimum bets to win the jackpot—that means you must bet more than the set bet minimum for you to stand a chance of winning that slot. Therefore, reviewing the bonus features and requirements for those bonuses before selecting a slot is always a good thing.

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