Casino glossary

Every term that turns up in the 62 school lessons, defined clearly. Hover any term inside a lesson and the definition pops up. Skim the categories below, search by name, or jump straight to a letter.

A

advantage play

Also: AP

strategy

Playing with a real positive expectation, typically through skill, information, or exploiting a structural flaw.

Advantage play means having a positive expected value against the house, usually by exploiting promotions, structural quirks, dealer signature, biased wheels, or card counting. It's legal in most jurisdictions but rarely welcomed; casinos are entitled to refuse service to known advantage players. Most so-called systems sold online are not advantage play; they're loss-shaping with the same negative EV.

American wheel

Also: double-zero wheel, double zero, 00 wheel

roulette

A roulette wheel with 38 pockets (0, 00, and 1 through 36). House edge 5.26%.

The American wheel adds a second zero (00). The extra pocket pushes the house edge to 5.26% on most bets and to 7.89% on the five-number basket bet covering 0, 00, 1, 2, 3. Empire Casino at Leicester Square is the most-cited London venue running American roulette.

B

banker

Also: banco

baccarat

One of the two main baccarat bets. Pays even money minus a 5% commission. House edge 1.06%.

Banker is the lower-edge of baccarat's two main bets. It wins slightly more often than Player, so the casino charges 5% commission on Banker wins. After commission, the house edge is 1.06%. Most baccarat strategy advice reduces to 'bet Banker, take the commission, ignore the Tie'.

bankroll

Also: roll

money

The money you've decided in advance you're willing to risk in a session or over a period of play.

Bankroll is the budget you've ringfenced for play. A session bankroll is what you'll take to the table that night. A career or trip bankroll is the larger figure across many sessions. Good practice is to set the figure before you play, not while you're playing, and to never reload from outside it.

See also: unit, table limit, ruin probability

basic strategy

Also: BS chart, blackjack chart

strategy

The mathematically correct play for every blackjack hand against every dealer up-card, given the rules of the table.

Basic strategy is the computer-solved correct decision for every blackjack situation. Following it perfectly reduces the house edge to roughly 0.40% under S17 DAS rules. Deviating from it costs you in expected value. The chart changes slightly with rule variations (S17 vs H17, DAS, surrender, deck count), which is why a printed chart is rules-specific.

See also: S17, H17, DAS, surrender, deviations

basket bet

Also: five-number bet, top line

roulette

American roulette bet covering 0, 00, 1, 2, 3. Worst standard bet in the game at 7.89% edge.

The basket bet covers five numbers on the American wheel: 0, 00, 1, 2, 3. It pays 6 to 1. Fair pay for covering 5 of 38 would be 6.6 to 1, so the rounding creates an extra-large house edge of 7.89%, the only standard roulette bet worse than the wheel's headline figure. Don't place it.

biased wheel

Also: wheel bias

roulette

A roulette wheel whose physical imperfections make some pockets more likely than others.

Wheel bias is a real historical phenomenon. Joseph Jagger famously exploited it at Monte Carlo in 1873. Modern wheels (Cammegh Mercury 360, TCS Saturn) are precision-engineered and monitored, with magnetic bowl checks and pocket-frequency analysis. Sustained, exploitable bias on a modern live casino wheel is extremely rare. Online RNG roulette is, by definition, not subject to physical bias.

burn card

Also: burn

table rules

A card discarded from the top of the shoe before play begins, to disrupt card tracking.

The burn card is removed face-down from the top of the deck or shoe before the round starts. In blackjack it's there to defeat card counters who have memorised the bottom of the previous shoe. In baccarat the burn is more elaborate, with the burn count derived from the first card flipped. It removes information; it doesn't change the EV materially.

C

Cammegh

equipment

British roulette wheel manufacturer. The Mercury 360 is the standard premium live wheel.

Cammegh is the British manufacturer behind the Mercury 360 roulette wheel, the leading premium live-casino wheel worldwide. The wheel includes Cammegh's BV9000 RFID system, magnetic bowl checks, and pocket-frequency monitoring designed to detect bias in real time. Used in most serious live studios and on most premium London tables.

card counting

Also: counting

strategy

Tracking the ratio of high to low cards left in the shoe to size bets and decisions when the deck favours you.

Card counting tracks how many high cards (tens, aces) remain in the shoe relative to low cards. When high cards dominate, the player edge rises; you raise the bet. The most common system is Hi-Lo, which assigns +1 to low cards and -1 to high cards. It's legal everywhere I'm aware of, but casinos can and do bar suspected counters. With a well-shuffled 6-deck shoe and aggressive penetration, a skilled counter can flip the house edge into a player edge of around 0.5% to 1.5%.

commission

Also: vig, vigorish, rake

baccarat

The 5% the casino takes on winning Banker bets in standard baccarat.

Baccarat charges 5% on Banker wins because Banker wins slightly more often than Player. The commission converts that mechanical advantage into the house's edge. It's tracked on a separate marker and settled at the end of the shoe. Some commission-free variants compensate by paying less on certain Banker results (typically 1 to 2 on Banker wins with a 6).

comp

Also: comps, comping

casino culture

Complimentary perk (food, room, transport) given to a player based on theoretical loss.

Comps are perks paid out of the casino's expected revenue from your play. The standard calculation: average bet times hours played times decisions per hour times house edge, multiplied by a percentage the host can return. London casinos comp coffees and meals freely; Las Vegas comps rooms and flights when the theoretical justifies it. Comps do not represent a player edge; they are a fraction of your expected loss returned to you in services.

continuous shuffling machine

Also: CSM

table rules

A device that constantly shuffles played cards back into the deck, eliminating card counting.

A continuous shuffling machine returns each played hand to a perpetual shuffler that feeds the dealer's next hand. It removes the concept of penetration: there is no shoe to count. CSMs are defeat-the-counter devices first and dealing convenience devices second. They also speed the game up, which raises the casino's hourly hold and the player's hourly expected loss.

See also: card counting, penetration, shoe

Crazy Time

online

Evolution live game show. Money wheel with bonus rounds. Volatile; house edges from 3.5% to 11.4% depending on bet.

Crazy Time is Evolution's flagship money-wheel game show. The main wheel has 54 segments paying out at varying ratios. Four bonus rounds (Coin Flip, Cash Hunt, Pachinko, Crazy Time) trigger when their corresponding segments hit and can produce very large multipliers. Theoretical RTP varies from about 96.50% on the best bet to 88.61% on the worst.

Crockfords

venue

Mayfair casino at 30 Curzon Street, originally founded 1828. Closed in 2023.

Crockfords was the oldest licensed casino club in the world by name, founded by William Crockford in 1828. It operated at 30 Curzon Street in Mayfair until closure in April 2023. The Phil Ivey edge-sorting case (UKSC 67) involved a £7.7 million baccarat session at Crockfords in 2012. The site sits empty as of writing.

See also: Mayfair, Phil Ivey, edge sorting

D

D'Alembert

Also: DAlembert, Alembert

systems

A progression that raises the stake by one unit after a loss, lowers it by one after a win. Same negative EV.

The D'Alembert assumes wins and losses tend to even out, so you raise stakes after losses and reduce after wins. The assumption is the gambler's fallacy. The house edge is unchanged. It feels gentler than the Martingale and is much less likely to produce a catastrophic loss in a session, but the long-run EV remains negative.

DAS

Also: double after split, doubling after split

blackjack rules

Table rule: you can double down after splitting a pair. Player-favourable.

DAS lets you double after a split. Without DAS, some pair-split cells in the basic strategy chart change to hits. Most modern shoes allow DAS. Worth about 0.14% to the player when available.

dealer signature

Also: section shooting

roulette

A predictable spin pattern from a particular dealer that can theoretically reduce uncertainty about where the ball lands.

Dealer signature is the theory that a specific croupier, releasing the ball with similar force at a similar wheel speed, will land it in a predictable section of the wheel relative to the release point. It is much harder to exploit in practice than in theory, requires hundreds of recorded spins, and is defeated by the dealer changing release habits or being rotated. Casinos rotate dealers in part to disrupt this.

deviations

Also: index plays, count deviations

blackjack rules

Departures from basic strategy that become correct at certain true counts when card counting.

Deviations are decisions where the chart answer is wrong given the current true count. The classic is 'insurance at +3 or higher' on Hi-Lo. Others include stand 16 vs 10 at TC +0, stand 12 vs 3 at TC +2, and double 9 vs 2 at TC +1. The 'Illustrious 18' is the canonical short list of the highest-EV deviations.

E

edge sorting

advantage play

An advantage technique exploiting microscopic asymmetries in card backs to identify high-value cards before they're dealt.

Edge sorting reads tiny manufacturing inconsistencies on the long edges of certain playing cards to identify cards before they're turned. Phil Ivey used it at Crockfords in 2012 to win £7.7 million at Punto Banco, then at the Borgata in Atlantic City for over $9 million. Crockfords refused to pay; Ivey sued. The UK Supreme Court ruled in 2017 (Ivey v Genting Casinos [2017] UKSC 67) that the technique constituted cheating in law, and Ivey lost.

en prison

Also: in prison

roulette

European roulette rule where an even-money bet is 'imprisoned' when zero lands, rather than lost.

En prison is the older form of La Partage. When zero lands, the even-money bet stays on the table for the next spin. If it wins next spin, the stake is returned; if not, it's lost. Mathematically equivalent to La Partage on a single decision but more complex over multiple spins. Rare in modern casinos.

European wheel

Also: single-zero wheel, single zero

roulette

A roulette wheel with 37 pockets (0 through 36). House edge 2.70% on every bet.

The European wheel has 37 pockets: zero plus 1 through 36. The house edge is 2.70% on every bet, because the wheel pays as if there were 36 pockets but actually has 37. Standard in London and continental Europe.

Evolution

Also: Evolution Gaming

studio

Swedish live-casino studio operator. Crazy Time, Lightning Roulette, Monopoly Live.

Evolution is the dominant live-casino studio. Listed in Stockholm, with studios across Latvia, Malta, Romania, Spain, the United States, Argentina, and Georgia. Its catalogue includes Crazy Time, Monopoly Live, Lightning Roulette, Dream Catcher, Funky Time, blackjack tables, baccarat tables, and game-show formats. Operators license Evolution feeds; you'll see the same dealers across multiple casino sites.

expected value

Also: EV

maths

The average outcome of a bet weighted by probability. Negative for every casino game except advantage-play exceptions.

Expected value is the long-run average result of placing a bet many times. A £100 bet on European roulette has an EV of about minus £2.70. The house edge is the EV expressed as a percentage of the stake. EV is not what happens on any single spin; it's the gravity the spins are falling towards.

F

Fibonacci

Also: Fibonacci system, Fib

systems

A roulette progression that follows the Fibonacci sequence after losses. Like the Martingale, mathematically harmless to the house edge.

The Fibonacci system bets according to the Fibonacci sequence after losses: 1, 1, 2, 3, 5, 8, 13. After a win, you move back two steps. It produces gentler escalation than the Martingale but the same long-run negative EV. The house edge is unchanged. The only difference is the shape of the bankroll path.

See also: Martingale, Labouchere, D'Alembert

G

gambler's fallacy

Also: Monte Carlo fallacy

psychology

The mistaken belief that past random outcomes affect the probability of future ones.

The gambler's fallacy is the belief that if red has come up six times in a row, black is now 'due'. It isn't. Each spin is independent. The fallacy gets its second name from a famous run at Monte Carlo in August 1913, where black came up 26 times in a row and players lost fortunes betting heavier on red each time it didn't break.

Gambling Act 1968

Also: Gaming Act 1968

history

UK legislation that codified casino licensing in Britain. Replaced the Betting and Gaming Act 1960's loopholes.

The Gaming Act 1968 (sometimes called the Gambling Act 1968) replaced the 1960 framework after Scotland Yard and the press exposed how poorly regulated London casinos had become. It introduced the Gaming Board and mandatory licensing, restricted advertising, set the conditions under which casinos could operate, and effectively created the modern London casino industry. Superseded for most purposes by the Gambling Act 2005.

Gambling Act 2005

regulation

Current UK legislation governing commercial gambling. Created the Gambling Commission.

The Gambling Act 2005 is the present-day framework for UK commercial gambling. It created the Gambling Commission, set out the three licensing objectives (preventing crime, ensuring fairness, protecting the vulnerable), and provided the structure for the 2014 amendments that brought offshore operators serving the UK under UKGC jurisdiction. The 2023 White Paper triggered the current wave of affordability and stake-limit reforms.

GamCare

responsible gambling

UK charity providing free, confidential support and the National Gambling Helpline.

GamCare runs the National Gambling Helpline (0808 8020 133, free, 24/7) and the free online counselling service. It's the first call for anyone worried about their own gambling or someone else's, and the most-cited UK responsible-gambling resource on regulated operator sites.

GAMSTOP

responsible gambling

UK national self-exclusion scheme that blocks UKGC-licensed operators from accepting registered users.

GAMSTOP is the UK's national self-exclusion register. Once you sign up, every UKGC-licensed online operator is required to refuse you service for the duration of your chosen exclusion (six months to five years). It does not cover non-UK operators. The companion scheme for land-based casinos is SENSE.

H

H17

Also: hits on soft 17

blackjack rules

Table rule: the dealer hits on soft 17. More favourable to the house.

H17 means the dealer hits on soft 17 (ace plus six). It's worse for the player by roughly 0.20%. Most Vegas Strip 6-deck shoes are H17. The chart cells that change versus S17: double on A,7 vs 2, double 11 vs A, and surrender 15 vs A among others.

host

Also: casino host

casino culture

A casino employee responsible for VIP and high-roller player relationships.

A casino host is your designated point of contact above a certain level of play. The host arranges credit, comps, transport, hotel rooms, and special access. They are paid on retention, so they have an interest in keeping you playing. None of this changes the maths; it changes the service around the maths.

house edge

Also: house advantage, casino edge, the edge

maths

The mathematical advantage the casino holds on a bet, expressed as a percentage of the stake the house keeps on average.

The house edge is the percentage of each bet, on average, that the casino keeps over a very long run. On European single-zero roulette it's 2.70% on every bet. On American double-zero it's 5.26%. On blackjack with perfect basic strategy and S17 rules it's around 0.40%. It does not predict any single result; it describes the long-run cost of playing.

K

Kelly criterion

Also: Kelly, Kelly fraction

maths

A formula for the optimal bet size that maximises long-run bankroll growth when you have a real edge.

The Kelly criterion gives the bet fraction that maximises the long-run geometric growth of a bankroll when you have a positive expected value. It applies to advantage play (card counting, sports betting at value prices) where the player has an edge. It does not apply to standard casino games where the edge is negative; nothing maximises growth when growth is impossible.

L

La Partage

Also: partage

roulette

European roulette rule that returns half your even-money stake if zero lands. Cuts the edge to 1.35%.

La Partage applies to even-money bets (red/black, odd/even, high/low). When zero lands, the player gets half the stake back instead of losing it all. Effective house edge on those bets drops from 2.70% to 1.35%, the best standard edge available at a UK land-based table. Aspers Stratford is the most-cited London venue applying La Partage.

Labouchere

Also: cancellation system, split Martingale

systems

A progression that writes out a sequence of numbers and bets the sum of the ends. Same negative EV as any other system.

Labouchere writes a sequence of numbers, say 1-2-3-4. The bet is the sum of the first and last: 5. A win crosses both off; a loss appends the bet to the right. The sequence closes when all numbers are crossed, locking in the original sum as profit. It can run a long way before resolving. Like every progression, it does not change the house edge.

live dealer

Also: live casino

online

Online casino games streamed from a real studio with a real dealer and physical equipment.

Live dealer games stream real croupiers and real equipment to your screen. Evolution, Playtech, Pragmatic Live, and Ezugi are the main studios. The maths is the same as a live floor (no RNG), but the production values, side bets, and 'extras' (like Double Ball or Lightning) reshape the betting menu.

live game show

Also: game show game, live entertainment game

online

Online casino game format with a presenter, big wheels, and gameshow staging. Crazy Time, Monopoly Live, Dream Catcher.

Live game shows are studio-produced casino games modelled on TV gameshow staging. Evolution dominates the category with Crazy Time, Monopoly Live, Lightning Roulette, Dream Catcher, and Funky Time. The house edges are typically worse than standard table games (often 4 to 8%), but the production keeps players engaged. They're entertainment that costs you something to watch.

See also: live dealer, house edge, Crazy Time

M

Martingale

Also: doubling system

systems

A betting progression that doubles the stake after every loss. Mathematically broken in every realistic setting.

The Martingale doubles your bet after each loss, intending to recover all previous losses plus one unit with the next win. It looks foolproof until you hit the table limit or the wallet limit, at which point a single losing streak destroys the bankroll. Eight consecutive losses on red, starting at £100, requires a £12,800 bet to continue. The house edge does not change. The system shapes the loss distribution; it does not eliminate the loss.

Mayfair

geography

The London neighbourhood between Hyde Park, Oxford Street, Regent Street, and Piccadilly. Historic home of British high-stakes gambling.

Mayfair is the area in the City of Westminster framed by Hyde Park, Oxford Street, Regent Street, and Piccadilly. It's where the high-stakes London casino tradition was concentrated for most of the post-war period: Crockfords, Les Ambassadeurs, the Clermont, the Colony. Several have closed; the postcode retains the reputation.

P

penetration

Also: pen

strategy

The fraction of the shoe dealt before the dealer shuffles.

Penetration is how deep into the shoe the dealer plays before reshuffling. 75% penetration on a 6-deck shoe means 4.5 decks dealt before the shuffle. Deeper penetration means counts get more reliable late in the shoe, which is when a counter's edge is highest. Casinos restrict penetration on tables where counters operate.

Phil Ivey

advantage play

American poker professional, central figure in the Crockfords edge-sorting case decided in 2017.

Phil Ivey is one of the most successful tournament poker players in history (ten World Series of Poker bracelets). His role in the Mayfair canon is the 2012 Crockfords baccarat session and the resulting Supreme Court case, Ivey v Genting Casinos UK Ltd [2017] UKSC 67, which redefined the legal test for dishonesty in English law (the 'Ivey test') and ruled edge sorting to be cheating, regardless of the player's subjective belief.

player

Also: punto

baccarat

One of the two main baccarat bets. Pays even money. House edge 1.24%.

Player wins slightly less often than Banker, so it pays the full even money with no commission. The house edge is 1.24%, marginally worse than Banker. Both bets are excellent by casino standards. The only meaningful difference is the commission accounting.

Pragmatic Play

Also: Pragmatic Live

studio

Malta-based supplier. Slots, live casino, and game shows. Mega Wheel, Sweet Bonanza CandyLand.

Pragmatic Play is a major content supplier. Slots are the headline product (Gates of Olympus, Sweet Bonanza, Sugar Rush) but the live studio has grown rapidly, producing Mega Wheel, Sweet Bonanza CandyLand, Mega Sic Bo, and live blackjack/baccarat tables. The studio is the main competitor to Evolution in the game-show category.

R

RNG

Also: random number generator

online

Random number generator. The software that decides outcomes in non-live online casino games.

RNG is the algorithm that determines results in online slots and virtual table games. Reputable casinos use audited certified RNGs (eCOGRA, GLI, iTech Labs are common testers). The output is statistically random within published RTP ranges. RNG roulette cannot have wheel bias because there is no physical wheel; it's just a uniform draw from 37 or 38 outcomes.

RTP

Also: return to player, return-to-player

maths

Return to player. The percentage of stakes a game pays back over a long run, the inverse of the house edge.

RTP is the long-run return to the player. A 97.30% RTP means the house edge is 2.70%. The two numbers describe the same thing from opposite ends. Slots commonly publish an RTP figure between 94% and 97.5%. Table games usually quote the edge instead.

ruin probability

Also: risk of ruin, ROR

maths

The chance that your bankroll hits zero before you stop playing.

Ruin probability is the chance that variance plus a negative expected value drives your bankroll to zero before you call it a night. It rises with bet size relative to bankroll, with the house edge, and with session length. The Martingale's headline flaw is a ruin probability that climbs rapidly once table limits or wallet limits are reached.

See also: variance, bankroll, table limit

running count

Also: RC

strategy

The sum of card-counting values seen so far in the shoe.

Running count is the cumulative total of card values in the shoe under your counting system. In Hi-Lo, +1 for low cards, -1 for high cards, 0 for sevens through nines. It's the raw input; you divide by decks remaining to get the true count, which is what you actually bet on.

See also: true count, card counting, Hi-Lo

S

S17

Also: stands on soft 17, dealer stands soft 17

blackjack rules

Table rule: the dealer stands on soft 17 (ace counted as 11). More favourable to the player.

S17 means the dealer stands on any hand totalling 17, including soft 17 (an ace plus a six). It's the more player-favourable rule, knocking about 0.20% off the house edge versus H17. Most London 6-deck shoes are S17. The basic strategy chart changes in a handful of cells between S17 and H17.

shoe

table rules

The dealing device that holds multiple shuffled decks of cards.

A shoe holds the prepared decks for blackjack or baccarat play, typically 6 to 8 decks. It's there to slow card removal and prevent dealer manipulation of the order. Shoe-dealt games are the standard in London. Single-deck and double-deck blackjack still exist but are rare and often carry compensating rule changes that make them no better for the player.

shuffle tracking

advantage play

Advantage technique of tracking clumps of high cards through the riffle shuffle.

Shuffle tracking watches favourable clumps of cards through the shuffle process to predict roughly where they'll be in the next shoe. It's much harder than card counting and requires deep familiarity with the specific shuffle a dealer uses. Modern automatic shufflers and continuous shuffling machines defeat it almost entirely.

side bet

table rules

An optional extra bet placed alongside the main bet, almost always with a much higher house edge than the main game.

Side bets are the casino's polite way of letting you pay extra for variance. Perfect Pairs and 21+3 on blackjack, Banker Pair and Player Pair on baccarat, Pair Plus on three-card poker. Most carry house edges between 3% and 15%, much worse than the base game. They exist because they sell, not because they're a good deal.

See also: house edge, perfect pairs, 21+3

surrender

Also: late surrender, LS

blackjack rules

Blackjack option: give up half your bet and forfeit the hand rather than play it out.

Late surrender lets you forfeit the hand after seeing the dealer's up-card, losing half the stake. It's correct in four specific cells in standard rules: 16 vs 9, 16 vs 10, 16 vs A, and 15 vs 10. Not all tables offer it. When available, it shaves about 0.07% off the house edge.

T

table limit

Also: limits, min/max

table rules

The minimum and maximum bet allowed on a given table.

Every table publishes a minimum and a maximum stake. The maximum is what breaks the Martingale: doubling bets hit the ceiling fast, and once they do, the system has no recovery mechanism. London limits vary: most main-floor tables run £5 to £500 or £10 to £1,000; high-roller rooms go much higher.

TCS John Huxley

Also: TCS

equipment

Major casino equipment manufacturer. Saturn roulette wheels, Chipper Champ chip sorters, table furniture.

TCS John Huxley is a long-established casino equipment manufacturer. Their Saturn wheel is the main alternative to Cammegh's Mercury. They also make the Chipper Champ chip sorter and table furniture used in many London venues. Headquartered in Surrey.

theoretical loss

Also: theo, expected loss

casino culture

The casino's expected profit from your play, calculated from your average bet, time at table, and the house edge.

Theoretical loss (or 'theo') is what the casino expects to win from you over a given amount of play. Average bet times hands per hour times hours times house edge. It drives comp eligibility and host tier. It is the maths from the casino's seat: what they expect to make, on average, from giving you a chair.

tie

Also: egalité

baccarat

Baccarat side bet that both hands tie. Pays 8 to 1 (sometimes 9 to 1). House edge over 14%. Don't place it.

The Tie bet pays 8 to 1 (sometimes 9 to 1). It's the highest-edge bet at the table at 14.36% or 4.84% respectively. Even the 9 to 1 version is roughly five times worse than Banker. The Tie is a trap dressed as a long-shot payout. Skip it.

true count

Also: TC

strategy

The running count divided by the number of decks remaining in the shoe.

True count is the running count adjusted for how much of the shoe is left. A running count of +6 with 2 decks remaining is a true count of +3 and a serious edge; the same +6 with 6 decks remaining is +1, much weaker. The true count is what tells you how much to bet.

U

UKGC

Also: Gambling Commission

regulation

Gambling Commission. The UK statutory regulator for commercial gambling under the Gambling Act 2005.

The Gambling Commission is the UK regulator, headquartered in Birmingham. It licenses casinos, sportsbooks, and online operators, sets responsible-gambling standards (including affordability checks, GAMSTOP integration, and advertising rules), and enforces against breaches. Its register of licensees is the first place to verify a UK-facing operator.

See also: Gambling Act 2005, GAMSTOP, GamCare

unit

Also: betting unit, base unit

money

The base bet size you've chosen as the standard increment for the session.

A unit is the standard bet size you use as a building block. £25 a unit, £100 a unit, whatever you've decided. Strategies and systems often describe bet sizes in units rather than money, because the maths is the same at any stake. Common guidance is to keep a unit below 1-2% of your session bankroll so variance has room to breathe.

V

variance

Also: volatility, swing

maths

The size of the bounces around the expected value. High variance means big short-term swings, both up and down.

Variance is the statistical measure of how spread out results are around the mean. A flat even-money bet has low variance; a single-number straight-up bet has high variance. High-variance bets create the biggest winners and the biggest losers in any given session. Over many sessions, variance fades and the house edge dominates.

W

wagering requirement

Also: playthrough, rollover, wagering

bonus

The amount you must bet through, expressed as a multiple of the bonus, before bonus winnings can be withdrawn.

Wagering requirements are how online casinos make bonus money sticky. 'Bonus subject to 35x wagering' means you must wager 35 times the bonus amount in qualifying play before withdrawing related winnings. Slots usually contribute 100%, table games often 10% or 0%. Verify the contribution table before you opt in. The maths almost always means the bonus is worth less than its face value.