GTO

(Game Theory Optimal)
strategy

A mathematically unexploitable strategy.

Pure GTO play is impossible to beat in the long run but doesn’t maximally exploit weak opponents. Most strong micro-stakes players play GTO-influenced exploitative poker.

See also

Range
The set of all hands a player could hold in a given spot.
EV
The average profit/loss of a play over infinite repetitions.
Bluff
Betting or raising with a weak hand to make opponents fold.
Check-Raise
Checking, then raising after an opponent bets.