Gambling glossary

Plain-English definitions of the terms used in our guides. Terms in the articles link here.

Updated November 12, 2026

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B

Banker bet

A baccarat bet that the banker hand will win. It pays 1 to 1 minus a 5% commission and has a house edge of about 1.06% with eight decks.

Bankroll

The total amount of money you have set aside for gambling. It should be money you can afford to lose.

Basic strategy

The mathematically best play for each blackjack hand against each dealer card under a given set of rules. It lowers the house edge but does not remove it.

Bonus buy

A slot option that lets you pay a multiple of your stake to trigger a feature, such as free spins, directly. It is restricted or unavailable in some markets.

C

Card counting

Tracking which cards have been dealt in blackjack to estimate whether the remaining cards favor the player. It is generally not treated as illegal but gives no guarantee, and casinos may refuse play.

D

Double down

A blackjack option to double your stake in return for exactly one more card.

E

Even-money bet

A bet that pays 1 to 1, such as red or black in roulette.

Expected value

The average result of a bet over many repetitions: each possible result multiplied by its probability, then added up. A bet with a house edge has a negative expected value for the player.

F

Free spins

Slot spins that cost no extra stake. They come either from a feature inside the game or from an operator promotion with terms attached.

G

Gambler’s fallacy

The mistaken belief that a run of one result makes the opposite result more likely. It is wrong for independent events such as roulette spins or coin flips.

Game contribution

The share of each stake that counts toward a wagering requirement, by game type. Slots often count 100% and table games far less.

H

Hard hand

A blackjack hand with no ace, or with an ace that must count as 1 to avoid going over 21.

Hit and stand

The two basic blackjack decisions. To hit is to take another card. To stand is to keep your hand as it is.

House edge

The average share of each wager that the casino keeps over a very long run. A house edge of 2% means an average cost of 2 per 100 wagered.

Hypothetical example

On this site, an example that uses invented numbers to show how a calculation works. It is not a measurement and not a forecast.

I

Independent events

Events where the result of one does not change the probability of the other. Roulette spins and slot spins are independent.

Inside bet

A roulette bet placed on specific numbers or on the lines between them, such as a straight-up bet, a split or a corner.

Insurance

A blackjack side bet offered when the dealer shows an ace. It pays 2 to 1 if the dealer has a ten in the hole and loses money over time, so basic strategy never takes it.

L

La partage

A roulette rule at some tables: when the ball lands on zero, an even-money bet loses only half its stake. It cuts the house edge on those bets to about 1.35%.

M

Martingale

A betting system that doubles the stake after every loss. It wins small amounts often but risks very large losses and does not change the house edge.

Maximum bet (bonus)

The largest stake allowed on one round while a bonus is active. Staking above it can lead to winnings being canceled under the terms.

Multiplier

A slot feature that scales a win by a factor such as 2× or 10×. In bonus terms, the number that multiplies the base amount to give the wagering requirement.

N

Natural

A two-card hand that totals 21 in blackjack (an ace and a ten-value card), or a total of 8 or 9 on the first two cards in baccarat.

O

Odds bet

A craps bet placed behind a pass or don’t pass bet once a point is set. It pays at true odds, so it adds no house edge of its own.

Outside bet

A roulette bet on a group of numbers around the grid, such as red or black, odd or even, a dozen or a column.

P

Pass line

The main craps bet. It wins on a 7 or 11 on the first throw, loses on 2, 3 or 12, and otherwise depends on whether the point repeats before a 7. House edge about 1.41%.

Payline

A line across a slot’s reels on which matching symbols form a win. The total stake equals the number of lines times the bet per line.

R

Random number generator (RNG)

A program that produces numbers that behave like random draws. A slot uses it to decide each spin before the animation shows the result.

RTP (return to player)

The percentage of money wagered that a game returns to players on average over a very large number of rounds. House edge = 100% − RTP.

S

Scatter

A slot symbol that pays or triggers a feature wherever it lands, not only on a payline.

Shoe

The box that holds the decks of cards dealt in blackjack or baccarat.

Side bet

An optional extra bet on a table game, such as the tie in baccarat or any seven in craps. Side bets usually carry a much higher house edge than the main bets.

Soft hand (soft 17)

A blackjack hand with an ace counted as 11, so it cannot bust on the next card. A soft 17 is an ace and a six. Whether the dealer hits or stands on it changes the house edge.

Split

A blackjack option to divide a pair into two hands, each with its own stake.

Stake

The amount you wager on one round, spin or hand.

Standard deviation

A measure of how far results typically spread around the average. A larger standard deviation means bigger swings.

Straight-up bet

A roulette bet on a single number. It pays 35 to 1.

Surrender

A blackjack option, offered at some tables, to give up a hand and lose half your stake instead of playing it out.

T

Table limits

The minimum and maximum stake allowed at a table. Maximum limits stop betting systems that rely on doubling.

U

Unit

The basic stake used to measure a bankroll and results. A budget of 200 at a stake of 5 is 40 units.

V

Variance

The average squared distance of results from the mean, which is the square of the standard deviation. In slot talk the word is often used loosely as another name for volatility.

Volatility

How unevenly a game pays. A low-volatility slot pays small wins often. A high-volatility slot pays rarely, but sometimes pays a lot.

W

Wagering requirement

The total amount you must stake before bonus winnings can be withdrawn: a multiplier times a base amount, such as the bonus or the deposit plus the bonus.

Ways to win

A slot format in which symbols pay on adjacent reels in any row instead of on fixed lines. A 5-reel, 3-row game has 243 ways.

Wild

A slot symbol that substitutes for other symbols to complete a win.