Modern online casino (try what she says) slots are controlled by computer chips and software, as well as the win percentages are preprogrammed in to the software.

Casino slots have Random Number Generators (RNG) which are continually generating combinations, regardless of whether the equipment isn't being played.

Running concurrently with the RNG of the casino slot machine is the payout percentage.

The payout percentage controls simply how much the slot machine will payout, for example the payout percentage may be 90%, meaning the slot game will payout 90% of all the bets played and the casino only gets to keep 10%.

This isn't to claim that every time you bet 10 credits you will get 9 in return - where is the fun and excitement in that? Instead the casino slot machine game will not pay out for a while, and after that suddenly go on a hot streak and you might hit a big jackpot.

So in essence the slot machine takes all the money played into it and pays it out to few lucky winners. The casino only gets to keep a relatively small percentage of all of the bets placed.

The casino slot software controls every involved in the machine, from the flashing lights to the spinning of the reels.

Whenever you hit spin on the slot machine, a combination is produced through the RNG which corresponds to the pictures on the reel.