Slot machines aren't the preserve of casino-goers across the UK and Vegas anymore: in 2017, you can enjoy video slots via your PC, Mac or mobile phone.

Instead of operating with mechanical number generators and physical 'one armed bandit' style machinery, online slots are programmed. Everything that goes on is done using a slick platform like Flash or HTML5. And the best games are licensed and checked for fairness.

What Is An Online Slot Machine?

An online slot machine pays out winnings by spinning virtual 'reels' on-screen and lining up matching symbols. Online video slots can feature all sorts of bonus rounds and jackpots, and the volatility of slots varies wildly from game to game.

Download (PC/Mac): Most modern online casinos let you download software to your desktop which contains a suite of games. Other slots can be downloaded individually to your casino app and played whenever you want. You will need a solid internet connection whenever you log on, however.

Instant-play (HTML5/Java/Adobe Flash): Other slots can be played via your web browser. This is a good option if you have a platform (like Linux, BlackBerry, or iOS/OS) that might not have its own dedicated version. Slots programmed in HTML5 work on desktop or mobile, and a variety of systems like Windows, iOS and Android. As such, it is a much more popular platform for game developers.

Random Number Generators and Audits

In physical, land-based slot machines, video slots sometimes have mechanical RNGs (Random Number Generators). These are programmed to stop the reels in a random spot on each spin. RNGs are tested but can work differently depending on the number of possible algorithms.

When a player hits the 'Spin' button, a set of algorithms are put into play, and a number selected at random. That number relates to a symbol on one of the five reels (or however many there are on the slot). The process is repeated for all reels. If a player matches two or more symbols starting from the left-most reel, they win a prize.

In some slots, paylines run from right to left too to create more possible combinations.

Managing Payouts & Paytables

Before you start playing, check the game's paytable. Each slot has one, and you'll find it on the Information page. Here you'll see all the possible paylines in the game as well as payouts and jackpots for each symbol. Give them a good read as you can see how generous or volatile the slot is.

For example, if a slot is fairly stingy on wins for matching two identical symbols, but pretty generous for its jackpots (hitting five symbols in a row) you know it's going to be a fairly volatile slot.

Special Symbols And Jackpots

Most 5-reel online slots have special bonus symbols that can increase your winnings:

Wilds: Wild symbols substitute for all regular icons on a payline. In some cases, the Wild will have a multiplier attached (usually 2x the total win). Wilds can also perform tricks to increase wins. They might expand to fill the whole reel, replicate themselves onto other reels, or stay in place during a free spins.

Scatters: Bonus Scatters are special icons that pay out whenever they land on a reel. They don't need to be part of a winning payline to award a prize. In bonus slots, three or more Scatter icons will trigger a special feature like Free Spins, a Trail Bonus, or a 'Pick Me' style game. You can find more about these bonus features on our dedicated pages.

Progressive Jackpots: The beauty of online slots is that they can often be played in conjunction with other casinos. Linked jackpot slots, or 'progressives', have special prizes that are pooled from bets made by players across multiple sites. And because these progressive jackpots are often "seeded" at £10,000 or more (in the case of some of the biggest) the total payouts can be enormous.

Progressive jackpots are usually triggered by hitting a special series of symbols, or a secondary 'Wheel of Fortune' game might have to be played first. Pick the right symbols, or spin the prize wheel correctly, and the big jackpot is yours.

Earning A Slots Casino Bonus

Online slots are getting more and more advanced. The bonus rounds are more original, the graphics and animation better, and the payouts better. And with more players enjoying specially-tailored games on their mobile phones and tablets, the progressive jackpots can be huge.

But even if you're not playing at the massive stakes, you can still access a good slots bonus online. Casinos offer all players some kind of deposit bonus which matches your deposit 100% when you play enough games within the deadline. Slots tournaments, meanwhile, can award big prizes if you bag enough wins during the promotion. 

Online Slots FAQs 

Can I Play Video Slots Online?

Yes. All casinos let you play a range of themes and styles, from 3-reel "classics" to 5-reel 3D games and even 7-reel giants. Graphics are animated using browser-friendly platforms like Adobe Flash and HTML5.

How Are They Random?

Online slots spins are governed by RNGs (Random Number Generators) that make sure each spin is fair.

Are They Fair To Play?

RNGs are also tested independently by testing labs like eCOGRA.  You can often read certificates of proof from a testing agency on the casino homepage. RNG testing labs also make sure long-term payouts on games are reliable.

Can I Win Decent Payouts?

Yes. Common slots jackpots can be 1000/1 for hitting five matching symbols on a single payline. However, jackpots worth 10,000/1 and above are also found at many 5-reel online slots. Bonus features like free spins can award hundreds of thousands of coins, while progressive jackpots can run into the millions.  

Can I Play For Free First?

Yes. Most slots are available for Practice Money before you commit with real cash. In some cases you won't even have to log in to give a game a try.

Do I Have To Download Software?

No. Many casinos have two options: a download app that stores all your favourite games on your desktop for easy access or an "instant-play" client that operates via the web browser. To use a web casino, just log in via the casino's homepage.

Can I Play On My Mobile Phone?

Yes. Many casinos have mobile download apps for iOS and/or Android devices. You can also play slots via your tablet or smartphone browser. Games are specially adapted for the smaller touch-screen but are still as playable and fun.