Strategy
Weak square
A square that can no longer be defended by a pawn, inviting an enemy piece to settle there.
When pawns advance past a square, they can never guard it again. If the opponent can occupy that square with a well-supported piece, it becomes an outpost against you.
Whole opening choices revolve around creating or avoiding weak squares — the holes on d5 or d6 in many Sicilians, for example.
Why it matters
Recognising the weak squares in a position tells both players where the pieces belong.
The mistake everyone makes
Grabbing space with pawn advances that leave gaping holes behind them for enemy knights.
Related terms
Outpost
A square in or near enemy territory, protected by a pawn, where a piece can sit untouchable.
Pawn structure
The arrangement of the pawns, which shapes the plans available to both sides.
Strategy
The long-term plan — where pieces belong and which structures to aim for — as opposed to tactics.
Prophylaxis
Preventing the opponent's ideas before pursuing your own.
See Weak square in your own games
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