Open

The first raise before the flop, made after everyone before you has folded.

Last updated October 16, 2026

What it means: To open is to make the first raise before the flop when every player before you has folded. The raise itself is called an open, and the player who made it is the opener.
How it is calculated: A label such as "CO opens" means the cutoff raised first, and "BTN vs CO open" means you are on the button facing that raise. A raise over an open is a 3-bet, and an all-in over one is a re-shove.
Worked example: UTG, the hijack and the cutoff fold, and the button raises to 2.5bb. The button has opened, and the blinds now face an open.
Why it matters: Most hands start with an open, so spot names lean on the word. Knowing who opened tells you whose range is strongest and who acts last after the flop.