Find out what makes a great online slot, learn about the various types of slots available, read the reviews and avoid mistakes with our tips and tricks

Online slot machines resources

In comparison to roulette and blackjack, slot machines are a new addition to the casino. However, in the world of online gambling, there is no question that slots rule supreme.

The number of slot games casinos offer varies greatly. There are sites with around 150 games and others with over 2,500 different titles.

Modern players are blessed with more than 70 iGaming software developers producing an array of titles, each pushing the boundaries of digital technology to make their ones more entertaining and more immersive than ever before.

List of online slot machines resources

How to play slot machines online

Players can get up and running playing online slots in a matter of seconds. All that is involved is setting up how much you wish to bet on each spin. It will depend on the exact game you are playing as to how to do this.

Some games use a "bet level" and "coin value" system whilst others have a straight forward "cash values" format. Also, certain ones are fixed paylines and some are not, so you may have to set that as well.

You can then decide if you wish to set the game up on autoplay. Here you will decide on a set number of spins and the game runs until the spins are completed. It does cut-off if you hit a bonus round or another important feature, however.

Types of online slots

These kind of titles tend to drop into three categories although it depends on your casino of choice as to how it orders and lists them. However, most sites will offer the following:

  • Progressive Jackpot slots: essentially, these are standard games with a progressive jackpot feature added to them. There is no question that these titles are among the most popular in any gaming website and with a world record payout of €17,879,645.12 from a 25p bet, it's easy to see why.
  • Video slots: these make up the bulk of the games library at the majority of casinos. The principle of these games is the same as an old-fashioned cabinet machines with mechanical reels. However, because this variety is electronic, it has adopted the name "video slot". Stunning graphics, smooth gameplay and amazing bonus rounds are just a few of the reasons that make these titles so popular.
  • Classic slots: these are also digital games, but the aim of a true classic slot is to make it feel like a traditional "old" machine. Therefore, they will usually have a 3 by 3 reel set and a limited number of paylines. Often the symbols used come from old-school designs, too. If you want something with a more retro flavour, then these are the games for you.

What are the rules?

There are few rules involved with online slot games. Players do need to be aware of the paytable as this will inform you of the:

  1. Paylines
  2. Value of each symbol
  3. Presence of a jackpot

Although not strictly a rule of this kind of games, if you are playing with bonus money, there will be a maximum bet limit enforced on slots. To ensure you don't invalidate your bonus, it's advisable to find this information out before playing.

Online slots features

In addition to the jackpot size, it is generally the extra features of an online slot that attracts players.

Developers have become very innovative in the games they create and modern players demand feature-rich titles to play. Among the top features to look out for are:

  • Free spins: all players love a free spins bonus round. These will be triggered by landing certain symbols in the base game. The number of free spins awarded varies from game to game.
  • Expanding wilds: the wild symbol is a vital element of most slots online. The expanding wild does exactly what it says on the tin; it expands to cover the whole reel so potentially creating more winning paylines. You can also get sticky wilds and walking wilds on some games. All of these definitely add an element of excitement to your play.
  • Multipliers: sometimes there are tremendous multipliers which really do boost up a player's winnings. Drive Multiplier Mayhem is a good example in this category. It uses x5 multipliers which then times together when in a winning combination.
  • Avalanche: this is one of the newer features that software developers have introduced. Symbols simply explode causing others to replace them and potentially form winning paylines.

Popular themes

Online slots come in all shapes and sizes. There is an extraordinary number of different themes, which means they cater to every taste.


Branded ones have become very common in recent years with plenty of famous movies such as Superman, Gladiator, Transformers, Jurassic World, Batman and Hitman each having video slots based upon them.

Other popular themes are celebrities, music bands, ancient Egypt, leprechauns, sport, animals (particularly safari) and many more.

Glossary: learn the language of the slot machines

Let's take a look at some of the most important terms related to the slot machines world with our glossary.

Slots may be the simplest online casino game, but they're also the most popular by a long way, with an estimated 80% of all players who sign up to gaming sites playing slots at some point.

Even though the games are easy and straightforward to play (click the link below to read our slots winners guide), there are some terms which it will help to be familiar with before selecting a game.

While slots require just the click of a button to get started, there are some "technical terms" which will make it easier to understand the various elements of the game.

Key terms

  • Auto-Play - Many games have an autoplay feature, meaning you don't have to manually click the 'spin button' every time you want to play. When you play your favorite you can usually select between 10 and 1000 auto spins, and on some more advanced slots you can even program the game to stop when you win or lose a predetermined amount
  • Bonus Rounds - These give you the chance to win extras. There are different types of bonus round ranging from free spins, sometimes with multipliers, to spinning wheels with prizes, like the TV game Wheel of Fortune, to pick'em rounds where you click a symbol and get awarded instant cash prizes or free spins
  • Coins - When you play slots you will select a number of coins to bet per spin, and the value of these coins. This will ultimately determine how much each spin costs. As you toggle the coin value and number of coins you will see the amount in your chosen currency changing. This is how much you will bet per spin. Wins are also paid out in coins and then converted into your currency
  • Free Spins - This is an extra feature built into many of the latest games, giving you the chance to spin and potentially win for free. A casino might offer you free spins on certain slots as part of a new player bonus package, but it is often possible to win free spins within the games themselves. This typically happens when you make a specific combination, and then a 'free spins' bonus round is triggered
  • Multipliers - These are another extra game feature, and are often triggered along with a free spins feature. Multipliers allow you to win bigger pots, multiplying the number of coins you win when you make a winning combination. For example, if you won 10 free spins with a x3 multiplier, everything you win during that bonus round would be multiplied by a fctor of 3
  • Paylines - Making winning combinations is the aim of playing slots, but the symbols don't have to match only diagonally. Paylines can be defined as different patterns of symbols you can make to win a cash prize, and on some games you can have as many as 50 active paylines, giving you lots of ways to win. Some games allow you to pick the number of paylines you want active during the game, while others will be pre-determined.
  • Progressive Jackpots - Progressive jackpots are larger jackpots which are set apart from base game jackpots. They are created when several games are linked together, and as more and more players spin on these across online casinos, the progressive jackpot grows. On games like Mega Moolah by Microgaming these can be millions of Euros
  • Reels - Most slot machines online are 5-reel games, meaning the game screen will be split into 5 sections, with symbols on each. The reels spin when you click the SPIN button, and you will see symbols landing on each one. The aim of the game is to get a matching symbol across the reels and win a cash prize
  • Re-spins - This is another built-in feature on many slot games, and it is triggered by making a pre-set combination of symbols. This causes the reels to automatically re-spin at no extra cost to you as the player, essentially giving you a free spin. Sometimes wild symbols will stick during re-spins, making it easier to make winning combinations
  • Scatter Symbols - Scatter symbols often trigger bonus rounds and special game features. For example, in the infamous NetEnt slot Guns n' Roses, if you get 3 scatter symbols (a vinyl record) on the reels, you will trigger the bonus round with a chance to win extras
  • Wild Symbols - Wild symbols can replace other game symbols, making it easier to make winning paylines. For example, if you get 4 of a certain symbol on reels 1,2,4 and 5, and a wild symbol on reel 3, you will have made a full winning payline straight across the reels

Grasping these concepts will make playing a lot easier, and will help you understand what you're getting into before selecting a game.

You don't need to be a brainiac to enjoy slots, and that's part of why they're so massively popular, but it still helps to know what features the game in question has, what you can win, and what it will cost to play. Get these terms into your head and you'll be able to pick better slots to play at any online casino.

Conclusion

Online slots are not for everyone, but there is no denying the quality of workmanship that goes into crafting these games. This particular niche has evolved so much in recent years and the games keep getting better and better.

A word of caution must be said, however. It is very easy to chew a big hole in your bankroll playing these games.

There are high volatility slot games that can go for extended periods without return much back to the player. Always play within your budget and treat them as a form of entertainment, as they are intended.