If you’re new to online casinos, the jargon can feel deliberately confusing — and sometimes it is. This glossary defines the terms that actually affect your money, in plain UK English, with no hype. Understanding these words is the difference between knowing what you’re agreeing to and hoping for the best.

For a fuller walkthrough, start with our beginner’s guide to online casinos. Below, the key terms are grouped by theme.

Bonuses & wagering

This is where most beginners lose money they didn’t need to. Read these carefully.

No-deposit bonus — A small bonus (cash or free spins) given without you paying anything in. It sounds like free money, but it almost always carries the strictest wagering requirements and low withdrawal caps, so the amount you can actually keep is limited.

Wagering requirement (playthrough) — The number of times you must bet a bonus (and sometimes the deposit too) before winnings become withdrawable. Shown as a multiplier like “35x”. A £20 bonus at 35x means £700 of total bets before cashout. The higher the number, the harder the bonus is to clear.

Free spins — Pre-set spins on a chosen slot, usually at the minimum stake. Winnings from free spins are nearly always treated as bonus funds, meaning they carry their own wagering requirement before you can withdraw them.

Game weighting — How much each game type counts toward wagering. Slots typically count 100%, while table games like blackjack might count 10% or even 0%. Bet £10 on a 10%-weighted game and only £1 goes toward clearing the bonus. This detail is buried in terms and quietly extends how long a bonus takes to clear.

Max bet (bonus) — The largest bet allowed while a bonus is active, often £5 or less. Breach it, even by accident, and the casino can void your winnings entirely. Always check this before playing with bonus funds.

Cashback — A partial refund of net losses over a period, paid as cash or bonus. Real-cash cashback with no wagering is genuinely valuable; bonus-style cashback with a playthrough is worth much less. Read which kind you’re getting.

For a deeper look at how these terms stack up across the industry, see our casino bonus wagering report.

Games & odds

These terms describe your actual chances. None of them can be beaten by “systems” or timing.

RTP (Return to Player) — The percentage a game is designed to return to players over the very long run. A 96% RTP means it keeps about 4% on average across millions of spins. It’s a long-term average, not a promise for your session — you can lose on a high-RTP game and win on a low one.

House edge — The flip side of RTP: the built-in mathematical advantage the casino holds. A 4% house edge means the game expects to keep 4% of everything wagered over time. Every casino game has one, and it never disappears. Our house edge explained guide breaks this down game by game.

Volatility (variance) — How a game pays out over time. High-volatility slots pay rarely but larger; low-volatility slots pay often but smaller. Volatility doesn’t change your long-term odds — it changes how bumpy the ride feels and how quickly a balance can swing.

Paylines — The lines across a slot’s reels on which matching symbols form a win. Modern slots may have hundreds, or use “ways to win” instead. More paylines usually means a higher total stake per spin, since you bet on each line.

Progressive jackpot — A prize that grows as players across many casinos contribute a slice of each bet, until someone wins it. The headline figures are large, but the odds of hitting one are extremely long, and chasing it costs real money every spin.

RNG (Random Number Generator) — The software that produces random, independent results on slots and digital table games. In a licensed casino, RNGs are tested by independent labs. Crucially, results are independent: a game is never “due” for a win after a losing streak.

Provably fair — A system, common on crypto casinos, that lets you cryptographically verify each result wasn’t tampered with after the bet. It proves a specific game round was fair; it does not change the house edge or mean the game favours you.

Payments

Straightforward terms about getting money in — and, more importantly, out.

Deposit — Money you add to your casino account to play. Once wagered, it’s genuinely at risk, so only deposit what you can afford to lose.

Withdrawal (cashout) — Moving winnings from your casino account back to your bank or wallet. Check the minimum withdrawal, any fees, and the processing time before you sign up — slow or capped withdrawals are a common complaint.

Withdrawal limit — A cap on how much you can withdraw per day, week or month. Large wins can take a long time to pay out fully under low limits. Bonus wins in particular often carry tight caps.

Pending (reversal) period — A delay before a withdrawal is processed, during which some casinos let you reverse it back into your balance. That reversal option is a trap — it’s designed to tempt you into gambling away money you’d decided to keep.

Safety & licensing

These terms protect you. Never play at a casino that fails on this section.

Licence — Authorisation from a gambling regulator to operate legally. A real, verifiable licence means rules on fairness, fund protection and dispute resolution apply. No licence means no protection if something goes wrong. Always confirm a licence is genuine and current, not just claimed.

KYC (Know Your Customer) — The legally required identity and age check before a licensed casino pays out. Expect to provide ID and proof of address. Complete it early — leaving KYC until your first withdrawal is the most common cause of delays.

Self-exclusion — A tool that blocks you from an account for a set period, or permanently, and that you cannot easily undo. It’s one of the strongest protections available if gambling stops being fun. Reputable casinos offer it, along with deposit limits and time-outs. Learn more on our responsible gambling page.

An honest closing note

No glossary makes gambling profitable — every game keeps an edge, and the terms above simply help you see exactly how. Knowing what a wagering requirement or house edge really means won’t tip the maths in your favour, but it will stop you being caught out by fine print.

If you’re just getting started, read the full beginner’s guide to online casinos next, and if you’d like help finding a genuinely fair, properly licensed site, try our AI casino finder.

18+. Gambling involves real financial risk. Only play with money you can afford to lose. Play responsibly.