Modern casino 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, even when the equipment isn't being played.

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

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

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

So in essence the slot machine takes all of 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 a component of the machine, from the flashing lights to the spinning of the reels.

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