A blocker is a card held by a player that makes it impossible (or less likely) that an opponent has a hand that includes that card (or a card of the same rank). Also known as card removal or combinatorics, blockers are a fundamental concept in poker game theory.
For example, if you hold A♠ K♥ and the board reads J♠ T♠ 2♠ 5♥ 6♦, it’s impossible for your opponent(s) to have the ace-high flush as you hold the A♠ blocker. Similarly, if you hold 7♥ 7♦ and the board reads 8♦ 6♥ 5♦ Q♠ K♠, it is significantly less likely that your opponent has a straight as you block half of the possible combinations of 9-7 and 7-4.
Want to learn the strategic value of blockers in poker? Read this guide:
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