Protected passed pawn
A protected passed pawn is a pawn that no enemy pawn can block or capture on its way to promotion and that has a friendly pawn diagonally behind it, ready to recapture if it is taken.
Two conditions must hold together. First, the pawn is passed: the enemy has no pawn on its own file or on either file beside it, so only pieces can stand in its way. Second, a friendly pawn guards it from the diagonal behind, which means anything that captures it is captured in turn.
That pairing explains why the structure is so valued in endgames. The pawn needs no help from your king or pieces, so they stay free for other work, while the opponent's king or a piece is chained to the square in front of it. In a pawn ending this often settles the game: your king walks off to win pawns on the other wing and the defending king cannot leave.
You can aim for one by exchanging pawns so that a passed pawn is left with a supporter, or by pushing a pawn past the enemy's pawns while a neighbor follows it up. The defender's job is to blockade, ideally with a knight, and to attack the supporting pawn with a lever, since removing it turns the passer back into an ordinary target.
Do not push it forward on reflex. Advancing takes it away from its guard, and a well-supported pawn that stays put can restrain the enemy for the whole game.
Compare it with Connected pawns. Connected pawns are two or more friendly pawns standing on adjacent files, side by side or on neighboring ranks, so that they can support each other as they advance.
It sits close to Connected passed pawns. Connected passed pawns are two passed pawns on adjacent files that support each other and can advance together, so the enemy cannot stop them one at a time and they often decide an endgame.
Where "Protected passed pawn" fits your own play is easier to judge with a coach reading your games; the first lesson is a paid one-on-one review that ends in a written plan.
Related terms
A passed pawn has a clear road to promotion as far as enemy pawns are concerned: none stands ahead of it on its own file or the two neighboring files, so the opponent must spend a piece or the king to stop it.
An outside passed pawn is a passer on a distant wing that works as a decoy: the defending king has to go and stop it, and the moves this takes let the other king win pawns elsewhere.
Connected passed pawns are two passed pawns on adjacent files that support each other and can advance together, so the enemy cannot stop them one at a time and they often decide an endgame.
A blockade is the plan of stopping an enemy pawn by occupying the square it must move to next, most often a passed or isolated pawn, with a piece that stays safe and useful there.
A pawn chain is a string of friendly pawns on a diagonal, each guarded by the pawn behind it, so only the rearmost pawn, the base, lacks pawn protection and becomes the usual target.
Connected pawns are two or more friendly pawns standing on adjacent files, side by side or on neighboring ranks, so that they can support each other as they advance.
Guides that go further
What to decide first, the questions to ask, what a first lesson should show and the red flags to avoid.
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