Online Slots: An Essential Glossary of Terms

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A slot machine reel against a golden background.
BetMGM Jun 19, 2024, 5:52 PM

It comes as no surprise that slots have emerged among the top online casino games, considering the sophisticated software and themes that developers are constantly introducing. These work to make gameplay more exciting and keep the masses returning to spinning the reels time and time again. While slots are relatively straightforward, there are some key terms you need to know if you want to master the art of choosing the best online slots for your taste.

Online Slots Glossary

While it may be a challenge to learn every gambling-related term, some are essential. If you’re heading towards a physical or virtual slot, these are the terms to know:

Active Payline

In some slots, players can choose which paylines they want winning combinations to land on. The selected paylines are known as active paylines, meaning they are part of the game and can secure wins for the player.


This allows players to automatically set a certain number of spins to play out without manually setting the reels in motion. Instead, the reels will automatically spin, often up to 100 times.

Bonus Game

Not to be confused with free spins, slots offer bonuses in various ways, such as mini-games within the slot game, to provide more winning opportunities.


A budget, also referred to as a bankroll, is the amount a player allocates to playing games. There are different ways to structure budgets to produce optimal results.  

Cascading Reels

When winning combinations form on cascading reels, the symbols involved in the win disappear from the grid and are replaced by new ones.

Classic Slots

This refers to the most traditional and simplistic type of slots, often containing basic symbols such as fruits, bars, and 7s, with no particular theme or elaborate graphics. These slots typically have only one payline.

Demo Game

A demo game has all the same functions and features as the slot game, but players can’t make cash bets. This is especially useful for novice players, as it allows them to practice without the risk of losing money. Although the player can’t claim winnings in a demo game, it’s a good way for them to become familiar with the game before playing online slots for money.

Expanding Wild

Regular wilds can replace any other symbols on the grid to form winning combinations. In the case of expanding wilds, when one wild lands on the grid, it expands to cover the entire reel and form even more winning combinations.

Fixed Jackpot

This is the set maximum amount that a player can win during gameplay. A fixed jackpot doesn’t fluctuate.

Free Spin

One of the most loved incentives at any online casino is free spins, which are additional rounds that don’t take any money from the player’s bankroll. They give the player more chances to win without decreasing their balance.

Hit Frequency

A hit is a winning combination, and the hit frequency is the rate or how often a particular slot secures a win for players.


Paylines are unique patterns integrated into a slot. When matching symbols land on a payline, they form a winning combination.

Pay Table

Whether you’re playing regular or jackpot slots, start at the pay tables, as they provide all the important information you need regarding the slot. You can usually find the pay tables on the top or bottom part of the screen.

Progressive Jackpot

These types of jackpots increase as players keep placing wagers. They keep growing in value, promising a substantial win at the end for whoever strikes it lucky.

Random Number Generator (RNG)

The unpredictability of online slots is part of their appeal, and nothing should be able to impact the game’s outcome, not even the grid (reels) configuration. Casinos use RNGs, software integrated into the slot, to randomize the results and ensure fair play.

Return To Player (RTP)

This is the average percentage of money the game pays out to players over a certain period, indicating how likely they are to receive returns on their bet. This theoretical average is calculated over millions of games, and players should only use the RTP as a guiding factor for deciding their chances of succeeding at a slot. The higher the RTP of a slot, the better. But remember, some of the best online slots aren’t always the best in returns.


Volatility ranges from low to medium and high. The variance indicates the frequency of payouts and the size of payouts. Low-volatility slots pay frequently but in smaller amounts, whereas high-volatility slots are for players with a higher risk appetite, as they offer substantially higher but less frequent payouts. There are several myths and misconceptions about the risk and reward aspect of slots, which you should read up on beforehand.


This term is often used interchangeably with “bet” or “stake,” referring to the amount placed by players.

Winning combination

When matching symbols land along an active payline, they form winning combinations. This helps the player progress in the game and increases the payout.

Spin the Reels to Success at BetMGM

Now that you have a better understanding of key online slot terms, you have the tools you need to approach the reels with confidence. BetMGM has a wide range of casino games to explore, from classic fruit-themed slots to more modern variations with exciting elements and graphics. Whatever your preference, you’re bound to find an online slot right up your alley at BetMGM. Simply register for a thrilling experience when you play casino online.

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Our BetMGM editors and authors are casino experts with a wealth of knowledge of the online casino industry at all levels. Their coverage includes company news, game reviews, how-to instructional articles, strategy guides, and editorials showcasing BetMGM’s superior product and game library.

Our BetMGM editors and authors are casino experts with a wealth of knowledge of the online casino industry at all levels. Their coverage includes company news, game reviews, how-to instructional articles, strategy guides, and editorials showcasing BetMGM’s superior product and game library.