Glossary · 55LL

Expected value (EV)

The average result of a bet if it were repeated forever. In commercial gambling EV is negative for the player by design — you expect to lose the house edge over time.

House edge

The built-in mathematical advantage the operator keeps: 100% minus the RTP. A 4% house edge means the game is designed for the house to keep 4% of turnover over time.

Reality of odds

Every commercial game is priced so the operator profits over time. There is no long-term winning "strategy" for pure chance games; the edge is fixed.

RTP (Return to Player)

The long-run percentage of total stakes a game pays back to players — e.g. 96% RTP returns £96 per £100 wagered on average across millions of spins. It never predicts a single session.

Volatility / Variance

How wildly outcomes swing around the average. High-volatility games pay rarely but large; low-volatility games pay often but small. High volatility can drain a bankroll fast between wins.

Gambler's fallacy

The false belief that past random results change future odds ("red is due after five blacks"). Independent games have no memory; each spin is fresh.

Illusion of control

Feeling that skill, rituals or "systems" influence a game of chance. It makes losses feel recoverable and encourages continued play.

Near miss

An outcome that looks close to a win (two jackpot symbols and a blank). The brain reacts almost like a win, which fuels continued play even though it is just a loss.

Reinforcement schedule

The pattern of rewards. Slots use "variable-ratio" reinforcement — unpredictable wins — which is the most habit-forming schedule known in psychology.

Chasing losses

Betting more to win back money you have already lost. It is one of the strongest warning signs of gambling harm and usually deepens losses rather than recovering them.

Gambling disorder

The clinical diagnosis (DSM-5) for persistent, harmful gambling that a person cannot control. It is a recognised behavioural addiction and is treatable.

Problem gambling

Gambling that disrupts or damages personal, family, financial or work life. It exists on a spectrum and can improve with limits, breaks and support.

Tilt

An emotional state — frustration, anger, desperation — that pushes you into bigger or faster bets and poor decisions. Walking away is the only reliable fix.

Affordability

Whether the money and time you gamble fit your real income and life. Gambling should only ever use disposable funds, never rent, bills, or borrowed money.

Bankroll

The fixed, pre-decided amount of money set aside for gambling as entertainment — money you can afford to lose entirely without affecting essentials.

Stake

The amount of money placed on a single bet. Lowering stake size is a direct way to make a bankroll and a session last, and to cut potential losses.

Blocking software

Apps such as BetBlocker or Gamban that block gambling sites and apps across your devices. Free options exist and add useful friction.

Cooling-off period

A deliberate pause before a bet or deposit — even a few minutes — that interrupts impulsive decisions and lets the urge pass.

Deposit limit

A cap you set on how much you can pay in over a day, week or month. One of the most effective safer-gambling tools — set it low and in advance.

Loss limit

A cap on how much you can lose in a period. When reached, play stops. Decide it while calm, not mid-session.

Reality check

An on-screen reminder of how long you have been playing and your net result, shown at intervals you choose. Turn it on and set it short.

Reinstatement / re-opening

The process (often with a cooling-off delay) to lift a self-exclusion. Deliberate friction here is a safety feature, not a bug.

Self-exclusion

A formal request to be blocked from gambling for a set time — with one operator, a national register (e.g. GAMSTOP, BetStop), or blocking software.

Time-out

A short cooling-off break (e.g. 24 hours to 6 weeks) offered by most operators, during which you cannot log in or bet.

Bonus

Promotional credit or free spins offered by operators. Almost always carries wagering requirements, caps and time limits that make it worth far less than the headline figure.

Wagering requirement

How many times a bonus (and sometimes deposit) must be bet before winnings can be withdrawn. A "£20 bonus, 40× wagering" needs £800 of bets first.

PGSI

The Problem Gambling Severity Index — a nine-item questionnaire scored 0–27 that classifies gambling risk from non-problem to problem gambling. Used in our free self-check.

Session

A single continuous period of gambling. Setting a time and money limit per session — and a hard stop — is a core safer-gambling habit.

The words casinos use

Odds & maths