A pawn that has been left behind by neighboring pawns and cannot obtain support from other pawns. Without nearby pawns to advance and protect it, it becomes isolated and vulnerable. The square in front of it can be used as an outpost by the opponent. It is susceptible to attacks from long-range pieces like rooks and bishops. It becomes particularly weak when on open or semi-open files. Difficult to defend, it often becomes a long-term positional weakness

A configuration where two or more pieces are aligned in a straight line (vertical, horizontal, or diagonal) to apply attacking pressure in the same direction. Common examples include rook+queen, bishop+queen, and rook+rook combinations

A pawn whose advance is obstructed by a piece. Knights are considered the ideal blockers, while queens and rooks are generally unsuitable for blocking. This refers not just to being blocked, but to being immobilized in a strategically disadvantageous way