Blackjack glossary

Ace

A card worth 1 or 11, whichever is better. It's what makes a hand "soft".

Basic strategy

The set of mathematically optimal decisions for every hand against every dealer upcard.

Blackjack (natural)

Ace + a ten-value card as the first two cards. Pays 3:2 at a good table.

Bust

Going over 21. A player who busts loses immediately, even if the dealer busts afterwards.

Dealer

The casino's representative. Plays by fixed rules: hit to 16, stand on 17.

Double after split (DAS)

A rule allowing you to double a hand created by a split. Good for the player.

Double down

Double your bet and receive exactly one more card.

H17 / S17

The dealer hits (H17) or stands (S17) on soft 17. S17 is better for the player.

Hard hand

A hand with no Ace, or where the Ace must count as 1.

Hi-Lo

The most popular counting system: +1 for 2–6, 0 for 7–9, −1 for 10s and Aces.

Hit

Ask for another card.

House edge

The average share of each bet the casino wins over the long run. Around 0.5% at blackjack with basic strategy and good rules.

Insurance

A side bet offered when the dealer shows an Ace, paying 2:1 if the dealer has blackjack. Unfavourable without card counting.

Pair

Two first cards of the same value, which you may split.

Penetration

How much of the shoe is dealt before the reshuffle. The deeper, the more useful counting becomes.

RNG

100% software blackjack (random number generator). Cards are reshuffled every hand.

Running count

The sum of the Hi-Lo values of every card seen since the last shuffle.

Shoe

The box holding the shuffled decks, used in casinos and at live tables.

Soft hand

A hand with an Ace counted as 11 without going over 21, e.g. A-6 (soft 17).

Split

Turn a pair into two hands, with an equal bet on each.

Stand

Take no more cards and keep your hand.

Surrender

Give up your hand after the first two cards and get half your bet back. "Late" when only possible after the dealer checks for blackjack.

True count

The running count divided by the number of decks remaining. Measures the player's actual edge at a given moment.

Variance

How widely results swing around the average. At blackjack it dominates over any single session.

To put these concepts into practice: basic strategy, the full chart and Hi-Lo counting.