The rules for slots are one of the simplest set of rules for any casino game. There ARE no real rules. All the player has to do is drop coins in the slot and pull the handle or push the spin button.

The payoff table tells players what the winning combinations of symbols are for that machine and what each combination pays based on the number of coins put in for the spin. Players have a much greater chance of hitting any of the lower-paying combinations.

There are basically two kinds of slot machines: flat tops / straight slots, and progressives. These slots are essentially the same, but for one feature: flat tops will pay the winner a predetermined amount, whereas progressive slots have a jackpot that grows by a percentage of each coin played. Oftentimes a number of progressive machines feed into one jackpot where any machine in the group can win, and the jackpot grows into an astronomical amount. These groupings can be a number of machines in one casino, or can be tied to all of the same machines in a whole state. Progressive machines can be identified by flashing electronic payoff signs displayed either on top of the machine or above a grouping.

The most common machines have three reels, but casinos do offer machines with four or five. When it comes to the odds of winning what is most important are the number of reels a machine has, and how many symbols are displayed on each reel. Essentially, the greater the number of reels and symbols, the harder it is to hit the jackpot or any other winning combination. The number of symbols on each reel is programmed into the computer that operates the slot machine, and the actual number of symbols depends on the size of the jackpot that the machine offers. The reason for the programmed symbols is to make the jackpot rare enough that the machine will generate enough money to pay for the jackpot and yield a profit for the casino. Most machines are set to pay out anywhere from 83 to 98 percent of the coins that are played in the course of a pay cycle.

Some online casinos offer so-called progressive jackpots. That means that a jackpot builds as more and more players play the casino's progressive machines. The first person to hit the winning combination (e.g. 777 or others) wins the total jackpot. To be eligible for the jackpot you usually have to play the maximum number of coins. Then the jackpot resets to a lower value and starts to increase again as more people play.

The result of each spin of the wheels is determined by a computer program that generates random results. This is true for both online slots games and slot machines found in terrestrial casinos. The machines can easily be set by the casino to generate whatever payout they choose. For example, they may set it to 96%. That means for every 100 dollars bet, the machine will, on average, pay out 96 dollars. The other four dollars goes to the casino and that's how they make their profit. Of course, that’s just on average. It’s possible, if Lady Luck is on your side, to make hundreds or even thousands of dollars with just one spin. On some large progressive jackpots you can win even millions.