Deliberately abandoning the balanced baseline in order to punish a specific mistake you believe your opponent is making. Where an equilibrium strategy is built to be unbeatable by anyone, exploitative play is built to beat one person, and it accepts becoming beatable in exchange.
The structure is always the same: identify the tendency, then take the opposite extreme. Against someone who folds too much to river bets, you bluff far more often than any balanced strategy would. Against someone who never folds, you stop bluffing entirely and value bet thinner and thinner. Against a player who only raises with premium hands, you fold holdings that would be routine calls against a normal range.
The profit comes from the size of the deviation, and so does the risk. Every adjustment leaves a signature. Bluffing every river makes you exploitable by anyone who simply starts calling; folding to every raise makes you exploitable by anyone who starts raising. Against an observant opponent an exploit has a shelf life, and the skill is less in finding it than in noticing when it has stopped working.
Two disciplines keep it honest. Require real evidence — a tendency you have actually seen more than once, not a stereotype you brought to the table. And size the deviation to the strength of the read: a firm read justifies a large adjustment, a vague impression justifies a small one, and no read at all justifies returning to the baseline and waiting.