Every review on this site leans on a working vocabulary — RTP builds, hold-and-win rounds, gambling software licences, aggregators — that the industry rarely stops to explain. This page fixes that. It’s not a generic casino glossary: every term here is one we actually use when reviewing slot studios, defined the way we mean it, with the traps flagged. Bookmark it, or arrive from any review where a term links here.
Where to Play the Slots These Terms Describe
The Maths Terms
RTP (Return to Player)
The percentage of all money staked that a slot is designed to pay back over the long run — 96% RTP means £96 returned per £100 staked, measured over millions of spins, not your session. The single most quoted number in slots, and the most misused: it says nothing about how the returns are distributed (see volatility) and the published figure isn’t always the one you’re playing (see RTP builds).
RTP builds / reduced-RTP configurations
Most modern slots ship in several versions with different RTPs — a 96% headline build plus 94%, 92% or lower variants — and the casino chooses which to run. This is the recurring warning across our reviews: Prospect Gaming publishes every variant openly, while some studios’ games circulate in builds several points below the advertised figure. The only reliable check is the paytable inside the game at your casino. Our highest RTP providers page ranks studios on their real published numbers.
Volatility (variance)
How the returns are distributed. Low volatility means frequent small wins; high volatility means long dry spells punctuated by big hits. Two slots with identical RTP can feel completely different to play. A handful of studios build identities around one end of the scale — Nolimit City at the extreme high end, S Gaming deliberately at the low end.
Hit frequency
The percentage of spins that produce any win at all — a more honest companion to RTP that most studios don’t publish. Peter & Sons and Hacksaw Gaming are notable exceptions that print it per game.
Max win / max multiplier
The largest possible payout, expressed as a multiple of stake — 10,000x means £10,000 from a £1 spin. Marketing loves this number; remember it usually comes with astronomical odds (Nolimit City deserves credit for actually publishing those odds). Ceilings across our reviews run from a few hundred-x on low-volatility titles to 66,492x on Design Works Gaming’s Molten Hot 7s.
Paylines vs ways to win
Paylines are fixed patterns a win must land on (a classic slot might have 10 or 20). Ways-to-win systems count any left-to-right combination of matching symbols on adjacent reels — 243 ways on a standard 5×3 grid, up to 117,649 on Megaways.
Game Mechanics
Megaways
Big Time Gaming‘s patented reel engine, where each reel shows two to seven symbols per spin so the number of ways to win changes every spin. Licensed across the industry — our Megaways providers page ranks every studio building on it.
Hold & Win / Hold & Respin
A bonus format where special coin or symbol landings lock in place and award a set of respins that reset with each new coin; filling the whole grid usually pays a Grand Jackpot. The dominant format among several studios we cover — Prospect Gaming applies it to nearly its entire catalogue, and TaDa Gaming‘s Fortune series is built on it.
Cascading / tumbling reels
Winning symbols are removed and replaced by new ones falling in, allowing chains of wins from one spin. The engine behind Pragmatic Play’s Sweet Bonanza and much of the modern high-volatility catalogue.
Cluster pays
Wins come from groups of adjacent matching symbols (usually five or more touching) rather than lines or ways — the format of Push Gaming’s Jammin’ Jars and Play’n GO‘s Reactoonz.
Bonus buy / feature buy
Paying a multiple of stake (commonly 80–100x) to trigger the bonus round directly. Banned in the UK — UK players won’t see the buy button even on games that have one elsewhere. Some studios offer UK-legal alternatives that boost trigger odds instead, like Push Gaming’s Bonus Boost.
Jackpot ladder
A set of fixed tiered prizes — typically Mini, Minor, Major, Grand — awarded through a bonus round rather than a progressive pool. The structure behind Gameburger’s 9 Pots of Gold and countless hold-and-win games.
Progressive jackpot
A prize pool that grows with every bet across all connected casinos until someone wins it. Mega Moolah (Games Global) is the most famous network; Relax Gaming’s Dream Drop is the notable studio-owned modern rival.
Licensing & Regulation
UKGC (UK Gambling Commission)
Britain’s gambling regulator. Every studio reviewed on this site is checked against the UKGC’s live public register before we write a word — not cached exports, which routinely show licences that have since lapsed.
Gambling Software licence
The UKGC licence category for companies that make slot games. This is the minimum a studio needs for its games to be legally supplied to UK casinos under its own name.
Game Host (Casino) licence
A further UKGC permission for studios that also host their games on their own servers, rather than handing files to a platform. Many modern studios hold both this and Gambling Software.
Surrendered licence
A licence the holder has voluntarily given up — the register still lists the company, which is exactly how stale “licensed provider” lists mislead. Quickspin, iSoftBet and High 5 Games all show surrendered UK licences as of 2026; their games can still appear in UK lobbies via an aggregator’s licence, but the studios hold no direct UK permissions. Our new providers page lists the studios that failed this exact check.
MGA (Malta Gaming Authority)
The other licence most studios hold — Malta is the industry’s operational hub, and an MGA Gaming Service licence or recognition notice is a common companion to UKGC permissions.
RNG certification
Independent lab testing (eCOGRA, BMM Testlabs, GLI and peers) confirming a game’s random number generator behaves as declared. A condition of licensing, not a marketing extra — every UKGC-licensed studio’s games carry it.
The Business Side
B2B studio / provider / supplier
The companies this site reviews. They build games and license them to casinos; they don’t take bets from players. That’s why a studio’s licence type (Gambling Software) differs from a casino’s, and why “is this studio legit?” and “is this casino legit?” are separate questions.
Aggregator / platform
A middleman distributing many studios’ games to casinos through one integration — the main reason a small studio’s games can appear at hundreds of casinos overnight. It’s also how games from studios with surrendered UK licences can lawfully remain in UK lobbies: the aggregator’s licence covers the supply.
House studio / sub-brand
A studio operating inside a larger group, often sharing the parent’s licence. Common across our reviews: Gameburger and Triple Edge under Games Global’s entity; Prospect Gaming and Iron Dog Studio under 1X2 Network; Retro Gaming inside Spinomenal; Pascal Gaming inside SoftConstruct. The shared licence is worth knowing, because regulator action against the parent affects every brand under it.
Branded / licensed slots
Games built on genuinely licensed intellectual property — Triple Edge’s Lara Croft, Pascal Gaming’s Fortune Ronaldinho — as opposed to “tribute” themes that imitate a property without a licence. Real licences are expensive and rare for small studios, which is why we flag them in reviews.
Exclusive launch
A new game appearing at one operator before general release — a marketing arrangement that signals a studio’s commercial relationships. S Gaming’s run of exclusives with William Hill, Bet365 and Midnite is a current example.
Glossary FAQs
What’s a good RTP for a slot?
96% is the informal industry standard for headline figures. Anything published above 96.5% is genuinely generous; anything below 94% deserves a second look. But the build running at your casino matters more than the headline — always check the in-game paytable.
Is high volatility better than low volatility?
Neither is better — they’re different products. High volatility suits players chasing big multiples who can tolerate long losing stretches; low volatility suits longer, steadier sessions. RTP being equal, the money returned is the same, just distributed differently.
Why can’t I buy bonuses in the UK?
The UKGC ruled feature-buy options out in 2019 under its technical standards, with the wider package of online slot controls fully enforced from October 2021. Games with buy buttons elsewhere simply hide them for UK players.
What does it mean if a studio’s licence is surrendered?
The company gave up its UK permissions voluntarily — usually a market exit or restructure. Its existing games can still be supplied through an aggregator’s licence, but the studio itself no longer answers directly to the UKGC.
Are slots with certified RNGs actually random?
Yes, within the declared maths. Certification confirms the game pays as its published RTP and rules describe — it doesn’t mean outcomes are due, streaky or influenced by your play.
What’s the difference between a provider and a casino?
Providers (the studios we review) make the games; casinos offer them to players. Different businesses, different licences, different questions when something goes wrong.
Jack spent years in slot QA and platform integration before turning reviewer — reading studios’ maths sheets and RTP configurations was literally his job. Every definition on this page reflects how the terms are actually used in our reviews. More about Jack →