A short reference for the terms that come up most often across the site. Anything you spot missing, the editor takes glossary suggestions.

Affordability check
A UKGC requirement that operators monitor for play patterns inconsistent with what the customer can comfortably afford. In practice this means a soft check at lower thresholds and a documentary review at higher ones — payslips or bank statements — before play can continue at that level.
Bonus balance
Money credited as a bonus, kept separate from cash on the operator's ledger until wagering requirements are met. It cannot be withdrawn while it is still bonus and there is usually a maximum stake during turnover.
Curacao licence
A non-UK gambling licence frequently held by offshore casinos targeting UK readers. It carries no UK consumer protections, is not enforced by the UKGC, and operators holding only a Curacao licence do not appear in this site's comparisons.
Deposit limit
A per-day, per-week or per-month cap on how much money the operator will let you deposit. Lowering takes effect immediately; raising requires a 24-hour cool-off and explicit reconfirmation. Required by UKGC licence conditions.
Evolution
Evolution Gaming, the dominant live-casino studio in the UK market. Most live blackjack, roulette and game-show feeds at the operators listed here are sourced from Evolution.
GAMSTOP
The free national self-exclusion scheme covering every UKGC-licensed online gambling site. Register at gamstop.co.uk for six months, one year or five years. The cooling-off design means you cannot remove yourself early.
IBAS
Independent Betting Adjudication Service. The UKGC-approved alternative dispute-resolution body for gambling complaints — once an operator's own complaints process is exhausted, IBAS is the next step before formal regulatory escalation.
KYC
Know Your Customer. The verification operators must complete to confirm a player's identity, age and address. UKGC rules require this at account opening rather than at first withdrawal, which removes the old withdrawal-friction trick.
Live casino
Casino games — blackjack, roulette, baccarat, game shows — streamed in real time from a studio with a human dealer. UK-licensed feeds usually come from Evolution, Pragmatic Live or Playtech's Bucharest studio.
Match score
The percentage figure in this site's comparison table. It is a weighted score against the criteria on the homepage methodology section — UKGC footprint, player-protection tooling, live-casino depth, mobile build, studio breadth, bonus fairness, support and usability. Not an objective rating; an editorial one.
Provider / studio
The software house that builds a slot or live game, distinct from the casino operator that licenses and hosts it. NetEnt, Pragmatic Play, Play'n GO, Hacksaw Gaming and Big Time Gaming are the most common slot studios across the operators on this site.
Reality check
A pop-up that interrupts a session at a set interval — fifteen minutes, thirty, an hour — to display elapsed time and net spend. Required by UKGC; the default interval the operator picks for new accounts is a useful signal of seriousness.
RTP
Return to Player. The long-run average percentage of stake a game returns as winnings, published on the game's info screen. A 96% RTP slot returns £96 on every £100 staked across millions of spins; it tells you nothing about a single session.
Self-customer view
Operator slang for a single account record that joins casino, sportsbook and live activity together. It matters because deposit and loss limits applied to one product apply to all of them, which prevents the easy workaround of switching tab.
UKGC
United Kingdom Gambling Commission. The statutory regulator for all gambling in Great Britain since 2007. Operates the public licensing register at gamblingcommission.gov.uk where every UK licensee can be verified by name and account number.
Volatility
How spread out a slot's payouts are. High-volatility games pay rarely but in larger amounts; low-volatility games pay frequently but in smaller ones. Volatility and RTP are independent variables; a high-RTP game can still be very volatile.
Wagering requirement
The number of times a bonus balance (and sometimes the deposit) must be wagered before it converts to withdrawable cash. A 35x requirement on a £100 bonus means £3,500 of bets at the eligible game's rate before the balance is yours.