Acting last means acting with more information. You see what everyone else did before committing, which lets you control the size of the pot, bluff more accurately and fold more cheaply.
The effect is large enough that identical hands are profitable in one seat and losing in another. Winning players open far wider on the button than under the gun, and the gap between those two ranges is mostly about position rather than card strength.
Baccarat makes the same point in a game with no decisions at all: the banker acts after seeing the player's third card and wins 45.86% of hands against 44.62%. Acting second is worth 1.24 percentage points there without any skill involved.
Where the numbers come from
Related terms in poker
- Pot odds — The price a call is getting, compared against how often it needs to win.
- Outs — The cards remaining that would improve your hand to a likely winner.
- Equity — Your share of the pot, meaning how often you win it if the hand plays to showdown.
- Implied odds — The money you expect to win later if your draw comes in, beyond what is in the pot now.
- Button — The dealer position, which acts last on every postflop street.
- Cutoff — The seat immediately to the right of the button.
Where an entry quotes a number, that figure comes from the computed sections of this site rather than from another glossary, so the definition and the derivation cannot drift apart. Each entry links to the page where the number is worked out.