Outposts:
An outpost is a square which is protected by a pawn and which cannot be attacked by an opponent's pawn. Such a square is a hole for the opponent. In the below, d4 is an outpost, occupied by White's knight.
An outpost is a square which is protected by a pawn and which cannot be attacked by an opponent's pawn. Such a square is a hole for the opponent. In the below, d4 is an outpost, occupied by White's knight.