Why a casino glossary is worth your time
Every online casino uses the same shorthand: RTP, wagering, volatility, KYC, e-wallet, sticky bonus. None of these terms is complicated once it is explained, but seeing them for the first time inside a terms-and-conditions page is rarely the easiest way to learn. Understanding the language is the difference between knowing exactly what a promotion is worth and being surprised later by a rule you never read.
This glossary is written for UK players. In Great Britain, online casino play is regulated by the UK Gambling Commission (UKGC), and any operator offering real-money gambling to British residents must hold a UKGC licence. Advertising and promotions are also bound by UKGC rules and the Advertising Standards Authority (ASA) codes, which is why you will see clear terms, age restrictions and responsible-gambling messaging on compliant sites. Knowing the vocabulary helps you read those rules with confidence rather than skimming past them.
Game maths: RTP, house edge and volatility
RTP (Return to Player) is the percentage of all staked money a game is designed to pay back to players over a very large number of rounds. An RTP figure is a long-run statistical average, not a promise about your next session. A high RTP means the game returns more of the total wagered amount over time, but short sessions can still swing far above or below it.
House edge is simply the other side of the same coin: it is the proportion the operator expects to retain over the long run. If a game returns most of the stakes to players on average, the house edge is the remaining slice the casino keeps. Every commercial casino game has a built-in house edge, which is why the maths favours the operator over time.
Volatility (sometimes called variance) describes how a game pays out, rather than how much. A high-volatility slot pays less often but in larger amounts, so your balance can swing sharply; a low-volatility game pays smaller wins more frequently, giving steadier, gentler play. Two games can share the same RTP yet feel completely different because of their volatility. Choosing volatility that matches your budget and patience is one of the most useful things this glossary can teach you.
Fair play: RNG and game testing
RNG (Random Number Generator) is the software that decides the outcome of digital casino games such as slots, virtual table games and instant-win titles. A certified RNG produces results that are statistically random and independent, meaning each spin or hand is unconnected to the last. There is no “due” payout and no memory of previous results.
On UKGC-licensed sites, games and their RNGs are subject to independent testing requirements, and operators must use software that meets the regulator’s technical standards. This is the mechanism that underpins fair play: the outcome is not something the casino can adjust per player. When you see references to testing laboratories or technical standards in a casino’s footer, that is the assurance the RNG behaves as intended.
Bonuses decoded: wagering, free spins and sticky bonuses
Wagering requirement (also called a playthrough or rollover) is the number of times you must bet a bonus, and sometimes the related deposit, before any associated winnings can be withdrawn. It is usually written as a multiple. The key questions to ask are: what amount the multiple applies to, which games count towards it, and how long you have to meet it.
Game weighting matters here. Not all games contribute equally to wagering; slots often count fully while table games may count partially or not at all. A bonus that looks generous can be slow to clear if your favourite games carry little weight.
Free spins are a set number of spins on a specified slot, awarded with or without a deposit. Winnings from free spins are frequently subject to their own wagering requirement and often a cap on the maximum amount you can withdraw, so always check the terms attached.
Sticky bonus describes bonus funds that cannot themselves be withdrawn. You can play with them and withdraw winnings they generate (once any wagering is met), but the original bonus amount is removed from your balance when you cash out. A non-sticky bonus, by contrast, keeps your deposit and bonus more separate, sometimes letting you withdraw your own funds without triggering bonus conditions. Reading which type you have been offered prevents an unwelcome surprise at withdrawal.
For more on reading promotions safely, our Guides hub covers bonuses, payments and game types in further detail.
Accounts and money: KYC, e-wallets and limits
KYC (Know Your Customer) is the identity-verification process every UK casino must carry out. Operators are required to confirm who you are, your age and, in some cases, the source of your funds. Expect to provide proof of identity and address; completing KYC early, rather than at the point of withdrawal, usually means faster payouts. These checks are a legal and licensing requirement, not an obstacle invented by the casino.
E-wallet is a digital payment method that holds funds and lets you deposit or withdraw without sharing card details directly with the casino each time. E-wallets are popular for convenience, though availability and any conditions vary by operator. Always check which payment methods are accepted and whether a chosen method qualifies for a given bonus, as some promotions exclude certain options.
Deposit limits let you cap how much you can pay in over a chosen period, and they are a core responsible-gambling tool. UKGC-licensed sites also offer features such as time-outs, reality checks and self-exclusion. Setting limits when you open an account, while you are calm and clear-headed, is far easier than adjusting them mid-session.
Jackpots and prize structures
Jackpot is the top prize a game can pay. A fixed jackpot is a set amount that does not change. A progressive jackpot grows as a small portion of each qualifying bet is added to a shared pool, which can build to large sums before someone wins it and the pool resets. Progressives can be linked across many games or operators, which is how the headline figures get so big.
It is worth remembering that progressive jackpots are won rarely and at random; the large prize does not change the underlying odds of any single spin. Treat jackpot games as entertainment with a small chance of a big outcome, not as a strategy. The RTP, volatility and wagering principles above still apply.
Responsible gambling in the UK
Gambling must always be treated as entertainment, never as a way to make money or recover losses. You must be 18 or over to gamble in the UK. Set a budget you can comfortably afford to lose, use the deposit limits and time-outs that UKGC-licensed casinos provide, and take a break whenever play stops feeling fun.
If gambling is becoming a problem for you or someone you know, free, confidential help is available. Visit BeGambleAware at begambleaware.org, contact GamCare for support and advice, or register with GAMSTOP to self-exclude from all UKGC-licensed online operators in one step. You can also read our own guidance on responsible gambling.
FAQ
Does a higher RTP mean I will win more?
Not in any single session. RTP is a long-run average measured over a vast number of rounds. A higher RTP returns more of the total wagered amount over time, but short-term results are governed by chance and volatility, so they can differ widely from the published figure.
What is the difference between wagering and volatility?
Wagering is a bonus rule: how many times you must bet before you can withdraw bonus-related winnings. Volatility is a game characteristic: how often and how large the payouts tend to be. One is a condition on a promotion; the other describes how a game behaves.
Why do casinos ask for ID before paying out?
UK-licensed casinos are legally required to verify your identity and age through KYC checks. Providing your documents soon after registering, rather than waiting until you request a withdrawal, usually means your payout is processed more quickly.
What does a sticky bonus mean for my withdrawal?
A sticky bonus cannot itself be withdrawn. You may play with it and, once any wagering is met, withdraw winnings it generated, but the original bonus amount is deducted when you cash out. Always check whether a bonus is sticky or non-sticky before you accept it.
Are all online casinos in the UK regulated?
Any operator legally offering real-money online casino play to people in Great Britain must hold a licence from the UK Gambling Commission, and their advertising must follow UKGC and ASA rules. Always confirm a site is UKGC-licensed before depositing, and stick to operators that display their licensing and responsible-gambling tools clearly.