Under the gun — first to act preflop. Play only strong hands here.
MP
Middle position — a bit more freedom than UTG.
CO
Cutoff — one seat before the button; a good stealing seat.
BTN
Button (dealer) — acts last after the flop. The most profitable seat.
SB
Small blind — posts half a blind before cards; acts first after the flop.
BB
Big blind — posts the full blind before cards; closes the preflop action.
Key terms
BB (unit)
"Big blinds" — the standard unit for pots, bets and stacks. "Pot: 7.5 BB" = 7.5 big blinds. Also the name of the big-blind seat.
Blinds
Forced bets (small + big blind) that seed the pot before cards are dealt.
Preflop / Flop / Turn / River
The betting rounds: before community cards, then after the 3rd, 4th and 5th community card.
Check
Pass the action without betting (only if nobody has bet yet).
Call
Match the current bet.
Raise
Increase the current bet.
Fold
Give up the hand and any chips already invested.
All-in
Bet your entire remaining stack.
Pot odds
Price of a call vs. the pot size. Calling 5 BB into 20 BB = 5/25 = 20% — you need to win at least that often.
Outs
Cards still in the deck that improve your hand. Rough odds: outs × 2% per card to come.
3-bet
The first re-raise (bet = 1, raise = 2, re-raise = 3).
C-bet
Continuation bet — the preflop raiser bets again on the flop.
Kicker
Your side card that breaks ties. With A-K on A-7-2, the K is your kicker.
Range
The whole set of hands a player could hold in a spot, not one exact hand.
Effective stack
The smaller of the stacks involved — the most you can actually win or lose in the hand.
Bluff / semi-bluff
Betting with a weak hand to make better hands fold; a semi-bluff can still improve (e.g. a flush draw).
Hand rankings (best → worst)
Royal flush — A-K-Q-J-10, same suit
Straight flush — five in a row, same suit (9-8-7-6-5♠)
Four of a kind — Q-Q-Q-Q-7
Full house — three + a pair (J-J-J-4-4)
Flush — five of one suit (A-J-8-6-2♥)
Straight — five in a row, mixed suits (8-7-6-5-4)
Three of a kind — 9-9-9-K-2
Two pair — K-K-5-5-A
One pair — 10-10-A-7-3
High card — none of the above; highest card plays
Advanced concepts
Range vs. range
Don't try to guess one exact hand — think about the whole set of hands each player can hold given every action so far, and how the board hits those sets.
Nut / range advantage
Some boards favor one player's range. On A♠ K♦ Q♥, an early-position raiser holds all the sets and big two-pairs while a big-blind caller mostly doesn't. Whoever's range is stronger gets to bet more aggressively.
GTO vs. exploitative
GTO (game theory optimal) is a balanced, mathematically unexploitable baseline — mixed frequencies and precise sizings. Exploitative play deviates from that baseline on purpose to punish a specific leak, e.g. bluffing far more often against someone who folds too much.
Overbet
A bet larger than the pot (120–300%+), used with a polarized range — the nuts or a bluff — to put medium-strength hands in an impossible spot.
Geometric sizing
Sizing flop and turn bets so the river bet is exactly a pot-sized all-in — the smoothest way to get full stacks in across three streets.
Polarized check-raise
Check-raising your strongest hands plus equity-driven bluffs (flush draws, gutshots, backdoor draws), making it miserable for the continuation-bettor to keep going.
Double-barrel bluffs
Pick flop bluffs that can gain equity on the turn — e.g. 8♥7♥ on K♣ Q♣ 6♥, where many turn cards add draws that let you keep betting credibly.
Leveling
Level 1: what do I have? Level 2: what do they have? Level 3: what do they think I have? The goal is to think exactly one level above your opponent — not three.
Image crafting
Deliberately showing an early bluff to build a wild image, then tightening up and getting paid off later when you actually hold the nuts.