History of slot machines

By Rainbet
Published Feb 14, 2024

This article explains the history of slot machines and their etymology. The article also covers slot machine’s terminology and its evolution through the decades.

What is the history of slot machines?

The first slot machine, birthed in the late 19th century, marked the inception of an era that would evolve into a cornerstone of gambling culture.

Charles Fey, an American inventor from San Francisco, is credited with creating the Liberty Bell in 1895, a gambling device that set the blueprint for future slot machines. This pioneering machine had symbols like horseshoes and bells, and notably, the Liberty Bell itself, offering a jackpot that resonated with players for generations.

The evolution of slot machines in the 20th century saw significant milestones, notably with Bally's introduction of the Money Honey in 1964. This electromechanical slot machine revolutionized the industry by enabling automatic payouts without an attendant. The Money Honey's success paved the way for the eventual rise of video slot machines in the 1970s, with the Fortune Coin, introduced in Las Vegas, standing out as the first of its kind.

As the decades progressed, the fruit machine, or "fruit symbol," became iconic, often associated with the prizes of chewing gum and other sweets, like if it was a vending machine.

The transition into the digital era saw slot machines embrace computerization, leading to the sophisticated, feature-rich online casinos slots we see today.

Slot machine etymology

The term "slot" in slot machine originates from the slit or "slot" where coins are inserted to play.

This simple yet crucial feature defines the mechanics and the very essence of this gambling machine, inviting players to place their bets in hopes of hitting a jackpot.

Slot machine terminology

Here’s a list of terms commonly associated with slots:

  1. Reels: The vertical lines of symbols that spin when the game is played.
  2. Paylines: Lines across the reels that determine wins based on matching symbols.
  3. Jackpot: The largest prize available in a slot game.
  4. Wild Symbols: Symbols that can substitute for other symbols to create winning combinations.
  5. Scatter Symbols: Symbols that can trigger bonuses, often without needing to be on a payline.
  6. Free Spins: Rounds that players do not have to pay for, often triggered by scatter symbols.
  7. Bonus Rounds: Additional bonus games within a slot that offer extra chances to win.
  8. RTP (Return to Player): The percentage of all wagered money a slot will pay back to players over time.
  9. Volatility: The risk associated with a slot game, indicating how often and how much it pays out.
  10. Progressive Jackpot: A jackpot that increases each time the game is played but the jackpot is not won.

Slot machine technology

Slot machines operate on complex principles, central to which are RTP, volatility, house edge, and RNG. These factors critically define the gameplay experience, balancing the game's fairness and excitement.

Random number generator

An RNG is a core technology used in slots to ensure they are a game of chance, making each spin's outcome is entirely random and fair. This system guarantees the unpredictability of game results, upholding the integrity of casino gaming.

Payout percentage (RTP)

Return to Player (RTP) is a percentage indicating how much of the total money wagered on a slot machine is paid back to players over time. It quantifies the game's fairness and player's likelihood of winning.


Volatility in slot machines describes the risk associated with playing a specific game, indicating the frequency and size of payouts. High volatility slots offer larger wins less often, while low volatility slots provide smaller wins more frequently.

House edge

House edge represents the casino's average profit from a player's bet, indicating the mathematical advantage that the casino has over players in the long run. It varies between games, ensuring profitability for the casino.

Slot machine evolution

Initially designed as simple, mechanical devices, slots have become complex, software-driven machines that improve gameplay and engage gamblers more effectively.

The transition began with the first video slot, introducing a new era in casino games where digital screens replaced physical reels, offering a broader array of features and themes.

Modern slot machines, equipped with the latest technology, integrate immersive graphics, soundtracks, and interactive bonus rounds.

This evolution continued with the advent of online slots, marking an important shift towards online gambling. These platforms allow gamblers to enjoy a vast selection of casino games from the comfort of their homes, further expanding the reach and accessibility of slot gaming.

Online slots are based on the electronic slot technology to ensure fair play and random outcomes, bringing the casino experience to players worldwide.

Mechanical reels

The era of mechanical reels marks a foundational chapter in the history of slot machines, characterized by the physical movement of reels after a player pulled a lever.

These machines operated on a straightforward mechanism: gears and springs set the reels in motion, with symbols painted on each reel. When the reels came to a stop, the combination of symbols determined the payout.

Mechanical slot machines gained immense popularity for their simplicity and the tangible excitement they offered. Players enjoyed the physical interaction with the machine, the anticipation as the reels spun, and the instant gratification of seeing the outcome.

The appeal of mechanical slots wasn't just in the gameplay but also in the design and the auditory feedback, the clinking of coins, the spinning reels, and the sounds of wins. These elements contributed to the immersive experience, making slots a sought-after game of chance.


The era of computerization in slot machines represented an important shift from mechanical reels to digital operations, significantly improving gameplay and the overall user experience.

This transition allowed for more sophisticated games, with computerized slots capable of offering a wider variety of symbols, more intricate paylines, and innovative bonus features that were not possible with mechanical designs.

Computerized slots quickly gained popularity among players for their improved graphics, sound effects, and the introduction of progressive jackpots, which added a new level of excitement to slot gaming.

The ability to link machines for collective jackpots and offer larger payouts transformed how gamblers perceived slots, making them a centerpiece in casinos.

This technological advancement also meant that slots became more reliable and easier to maintain, further boosting their appeal.

Video slot machines

Video slot machines in the late 20th century marked a revolutionary leap in slot technology.

These slots replaced traditional mechanical reels with digital screens, offering a new world of possibilities for game design and features. Video slots became immensely popular for their engaging themes, dynamic graphics, and the introduction of multi-line and multi-coin play options.

Players were drawn to video slots for their interactive elements, such as bonus rounds and complex storylines, which provided a more immersive experience than their mechanical predecessors. The flexibility of video technology allowed developers to create a wide variety of games, appealing to a broader audience and increasing slots' popularity in casinos around the world.

Online casinos slots

The introduction of online casino slots revolutionized the gambling industry by using internet, that offer unparalleled accessibility and variety.

This era allowed players to enjoy their favorite slot games from anywhere, eliminating the need for physical presence in a casino. Online slots capitalized on the advantages of digital technology to provide a wider array of games, featuring diverse themes, innovative bonus features, and progressive jackpots that appealed to a broad audience.

The perception of online slots was overwhelmingly positive, as they offered convenience and flexibility unmatched by land-based machines.

When was the slot machine invented?

The slot machine was invented in 1895 by Charles Fey in San Francisco.

What did players win with the earliest slot machines?

With the earliest slot machines, players won items like cigars, drinks, or chewing gum, not cash prizes.

What is the most successful slot machine?

The most successful slot machine is Mega Moolah, known for its record-breaking jackpots.