Once upon a time, all slots could be classified as 3-reel machines. These 'Classic' games featured mechanical operations, minimal paylines and even fewer bonus rounds.
In the US they were called AWP (Amusements With Prizes) as chewing gum or gifts were won instead of real money.
And while the cherries and melons may once have referred to the flavour of the gum you won from the slot, nostalgia means that you can still find hundreds of 'classic' slots online or in your local casino.
But in this age of 5-reel video slots with 720 paylines and bonus rounds galore, is there still a place for the 3-reel slot?
Most 3-reel slots today are of the video variety (although even some video slots still have the old-fashioned mechanical one arm to spin the reels) but you'll still find old-school mechanical slots with physical reels in casinos around the world.
Generally, the 3-reel games carry just the one payline - across the centre - which makes for lots of small regular wins but few big jackpots.
This is why 3-reel machines are known for their fairly low volatility. You won't get rich hitting up a 3-reel machine but the casual wins can be OK.
And when it comes to bonus rounds, you can't beat a 5-reel game. Free spins, trail bonuses and wheels of fortune can all be triggered in a typical 5-reel video slot, while nothing even close will be available in a 3-reeler.
3-reel slots will also usually have a basic set of symbols, generally themed around fruit or BAR icons - just like the classic old-school machines from the early days of slots.
Don't expect animated icons or expanding Wilds in a 3-reel game; they're more concerned with red 7s, cherries and keeping everything simple.
As mentioned, 3-Reel games have lower volatility, more regular wins on a 3-reel game but less chance of bagging a massive prize.
But the differences don't just stop at volatility. The graphics and sound FX in a 3-reel slot will also tend to be much more basic and might trigger memories of big land-based casinos. The background FX might sound like a real casino or a simple jingle will play if you land a cash win.
Meanwhile, big developers may pack their 5-reel video slots with progressive jackpots - either triggered at random or by hitting a certain series of Scatters. In general, 5-reel games - with their larger number of paylines - are more expensive to play than 3-reel slots, but the rewards can be much greater.
If you're looking for 3-reel slots online, you won't be looking for long. Most online casinos cater for the classic taste and will provide games by more traditional developers like Aristocrat, Bally, IGT and Barcrest.
Before you risk your hard-earned dollars and cents playing 3-reel slots, try out our range of great free-money games here. At VegasSlots.co.uk we have a top selection of free-to-play slots so you can try out a game with no risk.
3-reel games are great for a quick game on the go, and won't hammer your PC when you try to play them via a browser. Simple games mean quicker play, and these classic games are ideal for those players not wanting to risk a massive bankroll.
Try out some 3-reel games today and see why it's not all 3D, immersive, animated video slots out there in 2016.