How Slot Machines Work: Principles of Slots

The first slot machine was created over a hundred years ago, and since then, this form of gambling has changed significantly. Machines have evolved from mechanical devices to modern online games. So, how do slot machines and slots in casinos function?

Types of Slot Machines in Casinos

Mechanical "one-armed bandits" are now almost never used: they can be found in Las Vegas casinos, where they are displayed as exhibits. Today, all machines in classic casinos have an electronic basis, and the lever for spinning the reels in some of them is merely a nod to tradition.

The principle of operation for mechanical and electro-mechanical machines involves the independent spinning of three reels on a single axis, followed by the stopping of the reels. If identical symbols appear on the visible part of the reels, the player wins.

In modern slot machines in land-based and online casinos, there is a visualization of spinning reels on the screen. These are fully electronic devices, and manufacturers are not limited by physical parameters when choosing the number of reels, rows, and lines for play. The most popular slots feature five reels with three rows of symbols.

Principles of Slot Machines in Online Casinos

Slots are the most popular form of gambling in online casinos. Their development is undertaken by software provider companies such as NetEnt, Microgaming, Novomatic (Greentube), Playtech, and Yggdrasil Gaming. These companies guarantee the randomness of the results of each slot spin. The computer program operates on the provider's side, while the casino merely provides access to the video slot interface. Thus, a licensed online casino cannot influence the player's chances of winning.

This scheme has allowed major providers to create progressive jackpot systems that connect machines into a single network. When a progressive jackpot machine is activated in any licensed online casino, a portion of each player's bet contributes to forming the jackpot.

Multi-million jackpots are paid not by casinos, but by the software providers. These are the general principles of how online slot machines work; however, the specific characteristics of the slots have a greater impact on the likelihood of winning.

Random Number Generator

Winnings on slot machines are calculated using a Random Number Generator (RNG). This program makes the outcome of the reels' spins unpredictable. The RNG continuously performs calculations, even when the game is not in play. As soon as the player presses the Spin button, the program produces a result. The resulting numerical value determines which symbols appear on the reels and in what order, thus affecting the player's earnings.

What is RTP

RTP (Return to Player) is a metric that indicates what portion of the money spent is returned to the player over an extended gaming session. For example, if a machine's RTP is 95%, then for bets totaling 100 rubles, the player should expect to receive back 95 rubles. However, RTP is a statistical measure that only applies to large data volumes and does not contradict the principles of gambling. A player may win a large amount after the first spin or may go a long time without winning. It is important to remember: the higher the RTP, the better it is for the player. Modern slots can have returns of up to 99%. RTP values of 97-98% are considered high, around 96% are average, and below 95% are low.

Top Slots with High RTP Percentage

Slot Machine            Provider                   RTP (%)

Dicey Fruits              Synot Games           98.13

Blood Suckers          NetEnt                      98

Snake                       Gluck-Gamevy         98

Bikini Queens           Manna Play              97.77

Golden Tour              Playtech                   97.71

Downtown                1x2 Gaming              97.7

Winning Combinations and Bonus Features

All slots use similar methods for forming winning combinations: a certain number of identical symbols must align on the game field according to established rules. Typically, three or more identical symbols are required on an active line to form a combination. In some cases, it is sufficient for identical symbols to be on adjacent reels or to touch in any position. The more symbols included in the combination, the higher the win will be. One of the key features of a slot machine is the presence of special symbols and bonus functions. Special symbols can be of three types:

• Wild (wild symbol): helps complete combinations of regular symbols. Sometimes it can create its own chains with high payout multipliers or act as a multiplier, allowing the player to achieve significant wins.

• Scatter (scatter symbol): forms paid combinations regardless of their position on the game board. It is sufficient for the required number of scatters to appear anywhere to activate the free spins mode, which usually brings the player substantial winnings.

• Bonus symbol: triggers a bonus round that differs from the main game and can yield large winnings. Bonus features make the gameplay more engaging and increase the slot's return.

The number of prize features includes a variety of mechanics, and their diversity is limited only by the developers' imagination.

The Future of Video Slots

Game software manufacturers continue to evolve. To maintain interest in games, developers are introducing new mechanics, experimenting with the number of reels, rows, and lines, as well as adding special symbols and unique bonus features. In the future, we can expect even more bonuses in machines, the spread of virtual reality-based slots, and gameplay that increasingly resembles traditional video games.