Squares inside territory that can no longer be defended or protected by a friendly pawn.
Why it matters
A weak square is one you can never defend with a pawn again. Pawns only move forwards, so every pawn move gives up the squares it used to guard, permanently.
Pieces can cover a weak square, but pieces get traded and have other jobs. That is why a weak square is a long-term problem while a badly placed piece is a short-term one.
See it on a board
Black's pawns have gone to f5 and d6, so no black pawn will ever cover e6 again. The knight there cannot be chased, only captured.
Checked: the position really has the feature described.
How to play it
- After any pawn move, ask which squares that pawn used to control and whether another pawn still covers them.
- Look for weak squares in front of the opponent's pawns, especially near their king.
- Get a piece there — a knight first choice — and make sure it cannot be traded off cheaply.
At each level
The same idea, said the way it is taught at each age.
Knight · ages 4–6
Pawns cannot move backwards. Before you push one, check which squares it was guarding and whether you can live without them.
Rook · ages 6–9
Weak squares matter most in front of a pawn and near a king. A weak square on the edge, with nothing around it, is usually not worth a plan.
What goes wrong
- Pushing pawns in front of your own king to gain a tempo, and leaving squares that can never be repaired.
- Occupying a weak square with a piece that is immediately traded off, which fixes nothing.
Questions people ask
- Are all weak squares serious?
- No. A weak square only matters if the opponent can actually get a piece to it and keep it there. A hole in the corner of the board that nothing can reach is a curiosity, not a weakness.