Weak square
A weak square, also called a hole, is a square that a player's own pawns can no longer guard, so an enemy piece can settle there without being challenged by a pawn.
Also called: hole
A weak square is one that you can no longer defend with a pawn. Pawns only move forward, so once the pawns on the neighboring files have advanced or disappeared, nothing behind them can come back to cover the square. If the square also lies in your half of the board, an enemy piece, most often a knight, can land there and stay.
Why it matters: a piece on a weak square is hard to dislodge, and it often attacks other pawns and pieces from a safe post. The weakness also tends to grow, since the defender has to keep pieces nearby to watch the square.
To exploit one, find the square, then route a piece to it. Check that your own piece will be protected, ideally by a pawn, which turns the square into an outpost. To avoid creating weaknesses, think twice before moving pawns on the files next to important central squares, and trade off the attacking piece when the opportunity arises.
The classic way to create one by accident is to push a pawn for a short-term gain, such as space or a quick attack, without noticing that it gives up control of a square that the opponent can use for the rest of the game.
It sits close to Najdorf structure. The Sicilian Najdorf pawn setup after ...a6 and ...e5, with Black pawns on a6, d6 and e5 against White's e4, which gives Black a firm grip on d4 but leaves a hole on d5 and a backward d6 pawn.
Compare it with Principle of two weaknesses. The principle of two weaknesses holds that one weakness can usually be defended, so the attacker creates or finds a second weakness far away, forcing the defender's pieces to cover both and eventually fail at one.
It sits close to Static advantage. A static advantage is a lasting feature of a position, such as a better pawn structure, a protected outpost, the bishop pair or a safer king, that does not vanish in a few moves and can be exploited slowly.
Where "Weak square" 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
An outpost is an advanced square, usually in the opponent's half of the board, that is protected by one of your own pawns and cannot be attacked by an enemy pawn.
A weak pawn is a pawn that is hard to defend with other pawns and so must be protected by pieces, making it a long-term target for the opponent.
The knight moves to one of the nearest squares that is not on its own rank, file or diagonal, an L-shaped jump, and it is the only piece that can leap over other pieces.
A color complex is a group of squares of one color around a king or pawn structure that turns weak when the defender has traded the bishop that guards them and left pawns on the opposite color.
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.
Hanging pawns are two neighboring pawns, typically c4 and d4 for White, cut off from the rest of their side's pawns because the files on either flank of the pair hold none of the owner's pawns.
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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