Random Number Generator
Modern slot machines are computerized. So the odds are whatever they are programmed to be. In modern slot machines, the reels and lever are present for historical and entertainment reasons only. A Random Number Generator determines the positions of the reels. The machine's software includes a Random Number Generator.
The RNG generates random numbers at an extremely high rate. As soon as the Play button is pressed, the most recent random number is used to determine the result. This means that the result varies depending on exactly when the game is played. The result changes every fraction of a second.
Some professional gamblers observe that the RNG does not actually generate random numbers. It turned out that The number sequence is repeated time after time. Poor programming is its reason. Pseudo RNGs with very long periods canbe built relatively easily. There is no computer that is able to complete a single period in the expected lifetime of the universe. The access to the pseudo RNG code and seed values was known to Ronald Dale Harris, a former slot machine programmer. He discovered equations for specific gambling games like Keno. The fact that the next set of selected numbers would be based on the previous games played was revealed. However, this is impossible for most machines, because the RNG picks numbers even when the machine is not being played. So the player cannot tell where in the sequence they are.

Percentage Of The Payout
Slot machines usually pay out as winnings 82–98 per cent of the money that is wagered by players. The term theoretical payout percentage is used to denote it. Jurisdictions influence the minimum theoretical payout percentage. Law or regulation typically establish it. A certain winning pattern is determined by every casino individually. It concerns the amounts they pay and the frequencies of these pay-outs. The main criterion for selecting the winning patterns on slot machines is that they should yield a certain fraction of the money played to the house. The players get the rest of the money.
A slot machine's software is written and the theoretical payout percentage is set simultaneously. Physical swap of the software is needed for changing the payout percentage after a slot machine has been placed on the gaming floor. It is done infrequently because this is a time-consuming process. Certain jurisdictions presuppose the EPROM to have a tamper-evident seal. It can only be changed in the presence of Gaming Control Board officials. According to other jurisdictions slot machines are randomly audited to ensure that they contain only approved software.
The Nevada Gaming Commission is working now with Las Vegas casinos on technology that would allow the casino's slot manager to change the game, the odds, and the payouts remotely. The change cannot be done instantaneously, but only after the selected machine has been idle for at least four minutes. After making the change the machine is locked to new players for four minutes, it displays an on-screen message informing potential players that a change is being made.

Machines That Are Linked
A group of machines offers a particularly large prize, or jackpot if they are linked together in a special way. Each slot machine in the group contributes a small amount to this progressive jackpot, awarded to a player who gets a specific combination of symbols. A single slot machine's jackpot is considerably less than the progressive jackpot.
Sometimes multiple machines form multiple casinos. In these cases, the machines may be owned by the manufacturer, who is responsible for paying the jackpot.

Near-miss Programming
The reel display of modern slot machines is controlled by computer software. That is why the slot machine can be programmed to display combinations that are close to winning combinations.
The term near-miss programming is used to denote this practice.
There is a related phenomenon that is also sometimes called near-miss. Winning percentages programmed into the slot machine control the chance of a winning combination appearing on a pay line. The combinations above and below the payline are all roughly equally randomly distributed. This means it is much more likely that a winning combination will appear above or below a pay line than on the pay line. This occurs if abbreviated physical reels are used to display a win pattern based upon the RNG. In video slot machines, virtual reels are used and the symbols that appear around the winning line are usually an accurate depiction of how the reels were mathematically modeled.
The Nevada Gaming Commission investigated the issue of a near-miss above or below the pay line. It was considered to be legal as long as the near-miss above or below the pay line was not specially programmed. That means that the possibility of near-miss occurrence should be equal to the possibility of any other combination. It is impossible to program the machine to show winning combinations more frequently than other combinations above or below the pay line.
In Australia near-miss programming, where a near miss is inaccurately displayed is not allowed either. Manufacturer's practices are audited by regulators with the help of stop motion cameras.

Slots Fraud
Sometimes mechanical slot machines and their coin acceptors seem to belong to cheating devices and other scams.
EPROM computer chips controls modern slot machines and coin acceptors have become obsolete in favor of bill acceptors. Different advanced anti-cheating and anti-counterfeiting measures have been taken to make it difficult to defraud these machines. An example of modern ways of slot machine defrauding is directing microwaves toward it to disrupt its proper functioning.

There are at least two types of slot players.
Persistent player.
The players of this type believe that very soon there will be a period when the machine begins to pay. Just a second and the coins will be flying all over the casino!
The player will play until the machine pays out. He must have found a machine that haven’t paid for a long period of time or he has inserted to many coins and has got nothing. They believe that a big win is sure to happen right now. They can’t leave the machine because as soon as they do it will burst forth and pay out large sums. Makes sense if you have lost 0. 00 and have yet to win. The machine can’t but paying.
Many years ago players have their own way of determining whether the machine has not paid out for a long period of time. They touch the coins to see whether they were cold or hot. If the coins where hot then the slot machine had not paid out in a while and to the chaser this was good as the machine was do. In fact the coins could be hot only because of the numerous lights that heated the coins.
The chaser.
The player thinks that the machine he is going to play is not a machine that never pays. Players feel more comfortable and confident because they have been reinforced with a win and gain trust in the machine. One can feel the atmosphere of comfort and trust between the machine and the player.

Slot machines have a vivid and diverse history. They came through a number of changes and improvement. But the objective and the principle of the game always remain the same. The player inserts coins in the machine and then wins or loses according to the outcome of the game.
In fact all slot machines are the same. They only differ in some peculiarities: odds, payouts, payout percentage and symbols. There are so many variatisn of slot machines that everybody can find something to his liking.
The main difference is the number of lines. Slot machines can be either single line or multilane. In single line slots, the machine has just one line of reels, usually with 4 or 5 wheels, while in multiline there are a number of reel lines. Multi line slots are more difficult to understand because you win according to the winning combinations on the paylines, which can be formed in many ways. Sometimes you don't win anything at all, and sometimes multiple combinations award you with relatively big winning money. Paylines can be different. They can be vertical, diagonal, zigzags and what not.
Jackpot is also a feature peculiar not for all slots. In jackpot games, the slot machines accumulate a fraction of every wagered bet into a virtual pot. So the jackpot becomes bigger and bigger with every bet. Jackpots can reach several hundreds of thousands dollars. A certain winning combination hits the jackpot, and the lucky gambler collects everything that the ones before him left behind.
Slot machines are historically played with coins. Online casino slot machines are no exception to that rule, even though bets might differ slightly. Like regular slots they have betting limits, which can be even lower than in real casinos. Slots are the easiest casino games. They don’t require any decision on the player’s part.
Online slot machines also have RNG, which exclude any possibility to cheat. That’s why slots are as fair as it is only possible.

Slot machines are honest because state gaming commissions make sure they are. What you can really doubt is the honesty of some manufactures.
In the old days, slot machines worked mechanically, with independent wheels spinning until they each stopped randomly. Modern slot machines differ form the old ones greatly. There is a chip inside of every slot machine, this chip is programmed to select numbers randomly. The numbers the computer selects correspond to the symbols that appear on the slot machine’s screen. There is a computer code. It generates the random numbers and determines whether the slot machine is loose or tight. The gaming inspector will examine the machine to make sure it will not deceive the player. That is, inspectors make sure that the machine pays off at the legal rate or better.
Because slot machines don’t pay off with every spin, it’s difficult for customers to tell whether a slot machine’s chip has been programmed to pay off less often than is legally required. The machines have to be examined before people begin to play them. Of course it is very difficult to examine every single machine, that’s why inspectors examine only brands. In the case of the approval of the brand the manufactures can produce the slot machines, even change them if it doesn’t go out legal bounds. Using their right to produce slot machines they insert different chips, which makes the machine pay less.
There is an example when there was inserted an illegal tip which doesn’t allow royal flushes. Or a chip that shows near misses of a jackpot. One the one hand the machine would never have a jackpot and the player would keep on playing. If you think that you have come across such a machine you have a right to complain. Be sure that inspectors will examine this very machine and the casino itself to make sure everything is ok. Manufacturers that cheat are fined or they can lose their license.

There are many types of slot machine configurations but all work according to the same principles - put the money in the slots and pull the handle! According to the main slot classification there are two types of slots. They are straight slots and progressive slots. The main principle of the straight slots is that you get paid according to the schedule listed on the machine itself. Straight slots in their turn can be divided into multiplier, bonus multiplier, multiple payline and buy-a-pay slots. The main principle of bonus multiplier slots is a bonus round, which becomes active if you play with maximum bets. When playing multiple payline slots remember that the number of coins being bet determines the winning amount. The Buy-a-Pay slots are profitable only if you place maximum bets. Progressive Jackpot is the main characteristic of the progressive slots. Progressive jackpot grows with each coin being bet. The jackpot total is posted above the machine and can grow to enormous sums of money.