It’s been over a century since the first ever slot machine, Charles Fey’s iconic Liberty Bell, was invented. And whilst modern online slots are practically unrecognisable from the machines of Fey’s time, the excitement of playing has never lost its spark.

In fact, with over 28 million of us now choosing to play online, it seems the thrill of the slot machine only ever gets better.

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The Excitement of Online Slots

It just takes a quick look at one of today’s online casinos to see what all the hype is about. These sites can pack in over 500 of the latest and greatest slot games, ready for you to enjoy at the click of a button or the swipe of a screen. From all the classic titles once featured on real casino floors (like Cleopatra and Rainbow Riches) to games based on your favourite blockbusters (such as Kong: The 8th Wonder of the World, Rocky and Top Gun), there really is something for everyone in the current slot market, and it's only getting better.

Technology has come a long way in the last few years and slots have improved significantly. We're seeing better graphics, more impressive features, and unique mechanics that simply wouldn't have been possible on the very first online slots. The BetSoft creation Spinfinity Man is a great example of this. It does away with the old-school slot mechanics and features and in its place it provides something more akin to  a video game, with elements of action, RPG, puzzles, and more. It's an interactive journey that shows the exciting innovation at the heart of these machines.

What's more, the highly competitive online casino sector and the need to be different and unique has compelled casinos to offer more slots than ever before. The average casino has around 300 to 600 video slots, along with stacks of table/live games, but some have over 3,000 and that number is growing.

Bonus Features on Video Slots

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With so many slots to play and so many different innovations to experience, everything can be a little overwhelming. It helps, therefore, to know what to expect. 

If you’re only just starting out as a slot player, it’s a good idea to try and familiarise yourself with the kinds of bonus features available in today’s slots. Not only will this help you decide which slots are likely to prove most rewarding when choosing one to play, but it’ll also help you make the most of these features when they do appear as you’re spinning.

Scan your eyes over our handy guide below to get quickly up to speed with the basics of slot game features.

Free Spins

Free Spins are by far the most common feature on video slots and can be found on the vast majority of games that have bonus features. Often triggered by the game's Scatter symbol, these features simply offer a number of free spins.

Players are typically escorted to another set of reels, on which there may be additional Wilds, symbols, multipliers and more. All of the money that is won during this feature is added to a pot and this is then released at the end of the round.

Chain Reaction

The Chain Reaction feature goes by several different names depending on where you're playing. Microgaming were one of the first developers to use it and they call it Rolling Reels, using it on their "Stars" series of games, including Football Star and Cricket Star. NetEnt refer to it as Avalanche, while other developers call it everything from Chain Reaction to Cascading Symbols.

This feature is built-into the base game. Every time there is a win, the winning symbols disappear and then the ones above fall into their place. New symbols are then added to the game reels from above and if there is another win this will happen again, and again. Sometimes, as is the case with NetEnt's Avalanche, this is accompanied by a growing multiplier.

MegaWays

The MegaWays mechanic was developed by Big Time Gaming, but it has been licensed to other developers and it has been used on countless slots. This mechanic can be added to an existing slot and use to transform it, turning something that has fewer than 100 paylines into something that has close to 120,000. It does this by randomising the number of columns and rows, which creates varying amounts of paylines for every spin. This is one of the most popular game mechanics out there right now and it has been used to improve countless popular titles.

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Super-Sized Symbols

These symbols vary in size, but they typically cover multiple symbol spaces, such as 2x2 or 3x3. They were used to great effect during the Spinata Pinata slot, which is where most players were introduced to them.

Wild Symbols and Reels

Wilds are used abundantly in video slots. They are symbols that can substitute for all others (although rarely for the Scatter or Bonus) and help to build winning paylines. They sometimes come with multipliers attached and can also trigger features such as Wild Reels, Expanding Wilds, Walking Wilds, and more. These features come to life during the Free Spins round, but they can also be features in themselves, triggered at random or when a Wild lands on the reels.

Pick-Me Round

The "Pick-me" or "Choose-me" round is a simple game of selection. Players are often tasked with clicking a series of objects, which then reveal cash prizes. One of the most common uses of this feature is to choose a series of symbols and to add the cash behind each one to a pot. This pot then grows and only stops when a "Collect" symbol is revealed, at which point the money is released and the round ends.

Interactive Bonus Rounds

Although rare, interactive bonus rounds are becoming more common and have featured on some of the best video slots released over the last few years. Simply put, these features give players a chance to interact, often in the form of a puzzle game or even a platform game.

More

There are more slot bonuses out there, but this list covers the main ones. Take a look at our guide to the very best online casino bonuses to discover how to collect big cash before playing your favourite slots nd unlocking these features.