Bad bishop

A bad bishop is limited by the arrangement of its own pawns. The typical case occurs when several fixed pawns stand on the bishop's color and form a pawn chain, meaning a diagonally linked group of pawns, that cuts off its routes. The bishop controls few useful squares, changes sectors slowly, and may end up doing little beyond defending those pawns.

Same-colored pawns do not automatically condemn a bishop. It may stand outside the chain, protect important weaknesses, or have a pawn advance available to open lines. Likewise, a bishop with many empty squares may still lack useful work. Concrete activity matters more than geometric appearance.

Ways to rehabilitate it

1. Advance or exchange the pawn blocking its main diagonal.
2. Route the bishop outside the pawn chain from the side.
3. Exchange it for a more active enemy piece when the trade improves the position.
4. Change the structure to create an open diagonal or new targets.

The comparison with a good bishop is relative to the current position. A bad bishop may be an excellent defender, and in some endgames with few pieces, keeping it matters more than activating it. The useful questions are what job it performs and whether a realistic improvement exists.