GTO (game theory optimal)
Also called game theory optimal
GTO (game theory optimal) poker is a balanced, mathematically unexploitable strategy designed so no opponent can profit by adjusting to how you play.
The idea comes from game theory: a GTO strategy mixes your bets, raises, and folds in the right proportions so that whatever an opponent does, they can't gain an edge against you. It's about being un-exploitable rather than reading any one player. Solvers (computer programs) crunch these balanced frequencies, which is why you'll hear strong players talk about "solver lines."
It comes up most when people debate how to play a spot "correctly" in the abstract, with no information about who you're up against. GTO is the baseline of perfect balance; the opposite approach is exploitative play, where you deliberately deviate to punish a specific opponent's mistakes (like bluffing a player who folds too much).
As a beginner, you don't need to memorize solver charts. Pure GTO actually leaves money on the table against weak opponents, because you make more against them by simply betting your strong hands for value and folding your junk. Treat GTO as a long-term north star for understanding why balance matters, and lean on simple, solid fundamentals first.
Example
You hold A-K on a K-7-2 board and bet two-thirds of the pot. A GTO strategy says you should make that same sized bet with a mix of hands here, including some bluffs like Q-J, so an observant opponent can never be sure whether you're betting a strong hand or air, and can't profitably call or fold against you.