empty chairs in front of arcade machines

Slot machines have a rich history, tracing back well over 100 years to the original Liberty Bell machine created by Charles Fey in San Francisco in 1899. This early three-reel, five-symbol machine established the fundamental mechanics used in today’s slots. In their early history as mechanical or electromechanical devices, slot machines employed physical reels with symbols painted onto them that would spin and then settle on a random combination. Winnings were determined purely by the arrangement of matching symbols after the reels stopped spinning.

Modern slot machines, such as those at 7 BitCasino, now incorporate fully digital displays and controls. 

Fundamental Components of Slot Machines

  • Reels. With 3, 5, or even more vertically spinning digital reels, online slots display multiple columns of symbols. Reel configurations vary between games, with some focusing on bonus special symbols and complex bonus features more so than the core spinning reels. But the reels remain the primary focus and center of all slot play.
  • Symbols. The set of symbols – often with familiar themes like lucky 7s, bars, fruits, special icons, etc. – are displayed on the reels and used to determine winning combinations and payouts. Their arrangement when the reels stop spinning dictates whether you’ll be cashing out or spinning again.
  • Winning combinations. Within a given pay table for each slot game, certain matching symbol combinations are designated winners. The more rare a winning combo, generally, the higher the payout.
  • Random number generator (RNG). Behind the flashy reels and symbols, an RNG algorithm selects each stopped combination randomly to ensure fair play. State-of-the-art RNGs ensure none of the reel-stopping combinations can be predicted or manipulated in any way.
  • Paytable. The pay table identifies winning combinations and the payouts associated with each one. All real money slots need to publish pay tables so players understand potential returns.

How a Spin Works: Under the Hood of Online Slots

Every slot spin boils down to a two-step process controlled by the game’s RNG engine:

  1. The RNG selects a random number combination mapped to a specific reel result.
  2. That combination is displayed when the reels settle into position after spinning.

Let’s say a slot has three reels, and each reel displays 10 possible symbols. That means there are 10 x 10 x 10 = 1,000 unique potential outcomes. For any given spin:

  1. The RNG will select a number between 1 and 1,000 randomly. This could be something like 394.
  2. The game interprets this, mapping 394 to a specific symbol combination – say, “Cherry, Bar, 7”.
  3. That result is then displayed on screen once the spinning reels come to a stop based on the RNG’s randomly selected mapped outcome.

The symbols will keep spinning until settling in this pre-determined result, dictated by that initial randomly chosen number from the RNG. This process repeats anew for every following spin.

Behind the scenes, the game’s software also checks whether the result qualifies as a winner against the game’s pay table, then awards any payout accordingly.

Modern online slots such as thereviewscasino.com build on this core underlying mechanic with expanding features like bonus rounds, special multiplier symbols, mini-games, and more – but ultimately still rely on this RNG-based, spinning reel dynamic at their core.

Slot Machine Odds and Expected Return

All legit real-money slot games must publish return-to-player (RTP) percentages that indicate the expected average payout percentage over time across all players. For example, a slot with an RTP of 95% means over time, for every $1 wagered on average $0.95 cents will be paid back out to players in winnings. The greater the RTP, the more player-friendly the game.

Of course, every spin is completely random with slots, so this RTP value reflects the aggregate payout percentage over time – not an every-spin guarantee. Individual spins that win $0 or $1,000+ are both possible with lower and higher RTP slots depending on the luck of that one spin’s random result.

For example, here are RTPs across a few popular online slot titles:

Game RTP
Starburst 96.09%
Gonzo’s Quest 95.97%
Mega Moolah 92.02%
Jackpot 6000 95.80%

Within any given game rules and math model, those RTP percentages will play out over time while still allowing for otherwise lucky or unlucky streaks on individual spins along the way.

How Bonus Features Alter Slot Odds

Many modern slot variants modify the standard spinning reel dynamic with bonus features like free spins, mini-games, multiplier wilds, and more. These can not only make slots more engaging and entertaining through added variety – but they can also impact the game’s base RTP.

For example, slots with bonus mini-games often feature slightly reduced base game payouts to fund much more rewarding bonus rounds. Or games with higher multipliers available – via features like expanding wilds that can cover entire reels with substituted wildcard symbols under the right conditions – effectively allow bigger payouts that raise the average return over time.

Final Take

Bonus features essentially expand the core spinning reels to incorporate a wider range of factors contributing to slot machine payout percentages. This lets developers tune overall game volatility – dictating how often wins occur, at what scale, and the overall hit frequency for players. The careful balance of these factors allows considerable variety across modern slot games.

But that original spinning reel mechanic established over 100 years ago remains the beating heart behind even the most flashy, feature-rich video slots today. Understanding the essential inner workings that drive your favorite slot games allows greater insight into some of gambling’s most enduringly popular attractions.