How Slots Work

How Online Slots Work

At first glance, the functioning of slot machines may appear to be a fairly self explanatory. Just a bunch of symbols spinning on reels and you win if they match, right? In reality, however, slots can become pretty confusing when you actually try to play them for the first time.

As if the flashing lights, colourful display (together with a cacophony of chimes and other sounds), and complex layout weren’t enough, the greater challenge is trying to understand what actually constitutes a win and how much each combination pays out. It also makes sense to either feel cheated or to imagine that there is some predictable system in place that you can beat if only you can figure it out.

So it is actually really important for you to know exactly how a slot machine or online slot works before you start the reels spinning. This knowledge will help you to make smarter decisions and get the most out of your slots experience.

First Impressions

Let’s start by demystifying the confusing picture presented by the slot machine/ online slot when you first approach it – i.e. the slot layout. Your screen or machine will usually display the following common features:

  • A number or vertical reels (usually three or five) displaying various symbols in horizontal rows (usually three or five);
  • The payout table.
  • Payline buttons;
  • An arm or play button;
  • A credit metre;

The reels of symbols are obviously the most familiar feature. The symbols they display will be based on a particular theme and will be front and centre in the display. It is important to note that, the more reels a machine has, the worse the odds become of any one payline being landed. (We’ll explain exactly how these reels work in a moment.)

You should begin your slot game by consulting the payout table, which will generally appear in the top left-hand-side corner of the display. This table will show you which symbols pay out, in which combinations (winning lines/paylines), and how much they pay. If the game features wilds, scatters or other bonus symbols, these should also be explained here.

Once you have consulted the payout table, you can turn to the payline buttons at the bottom of the display. These will present you with options for which lines you want to select and how many credits you wish to wager on each one. Note that some slots do not allow you to adjust the number of paylines and you must bet on all of them. Insert your coins or card and make your selection.

You are now ready to start playing by either pressing the start/play button or (on older slots) pulling the arm on the right of the machine, which will set the reels spinning. On some slots, you will also be able to select the auto-spin feature, which spins the reels automatically for a preset number of spins so you don’t have to keep pushing the start button. You may also encounter a stop button, which allows you to stop the reels, giving you the feeling that you can control the outcome if you are quick enough. As we’ll explain next, that is just a fun illusion.

While the reels are in play, you can monitor your credits by watching the credit metre next to the reels (usually in the top right-hand-side corner of the display). The credit metre may be accompanied by a winnings metre. (If you are playing on a really old-school machine, there will be a coin bin at the bottom of the machine, where your coins come tumbling out if you win – just like in the movies!)

The Science of Slots

Here’s where things get a bit technical. As we mentioned before, being able to stop the reels when they spin only creates the illusion of control. In reality, even the reels themselves are just for show. That’s because modern slots use a computer program called a random number generator (RNG) to generate the symbol combination every time you hit the spin button.

In fact, that random number generator works constantly and whatever combination you land depends on when you push the play button (at which point the combination most recently generated by the RNG is picked up) and not when the reels come to a stop. Since these sequences are completely random, there is no way of knowing which combination will come next.

Odds and Weighting

However, although the numbers generated by the RNG are completely unknowable in advance, the odds become predictable over a very long period of time, simply by virtue of the law of averages. So, based on this information, the casino is able to alter the weighting of the machine (using the EPROM) and adjust payline payouts to ensure that it stays in business while still complying with required legal payout percentages.