Thanks to VegasSlotsOnline, they have given the most concise answer to this question, which I have already answered in another article about slot machines. But to reiterate, the Random Number Generator is what make slots machines work in order to determine the outcome of each spin. You can’t “spin” this answer in any other way. When you spin the reels, the RNG makes the slot truly random. The myth that slot machines run hot or cold is also not true.
If you are playing classic or traditional slots, you will find they have 3 reels and one pay line. If you get all the same symbols on that one pay line, you win according to the symbol payout and the wager you made. There are also 5-reel slot variations such as bonus slots, jackpot slots, and progressive slots. These would have many pay lines, as much as 100. There are also slot games that pay all ways. The highest pay all ways is 1043, I believe. This simply means that no matter where the combination of three or more symbols shows up on the reels, you win.
The newer slot machines of today use a “weighting system.” This system determines when a “stop” will occur. For example: if you are playing a slot machine with 10 symbols, but one of the symbols is a special symbol, say a wild symbol, it may come up about once in every 100 spins. The odds, then, of getting three symbols can be as high as 1 in a 100 up to 1 in a million. There may also be other symbols that are programmed to come up half the time. But this is an ambiguous statement considering that online casinos have the highest percentage of Return to Player than land-based casinos. So the odds of getting three symbols is much greater.
The Par Sheet
This sheet will determine the odds. Every slot machine has one and the sheet will specify the weightings for each stop on the reels. The par sheet allows for the odds and the house edge to be made.
Pay Back Percentage
Here is where US players who play at Liberty Slots Casino, for example, can make huge wins. The RTP or return to player stats at Liberty Slots is 98.41%. This is the highest pay back percentage at any online casino.