Good bishop, bad bishop

A bishop is good or bad depending on the position of its own pawns. If most of the player’s pawns sit on squares of the opposite color from the bishop, the bishop is good — it has open diagonals, mobility, and influence. If the pawns sit on the same color as the bishop, the bishop is bad — its own pawns block its diagonals, and it cannot find active squares.

The French Defense is the textbook example. Black’s pawns on e6 and d5 (and often f7) sit on light squares; Black’s light-squared bishop on c8 is therefore bad. It is trapped behind its own pawns, has no useful diagonal, and must spend many moves trying to find an active square — or be exchanged. The French middlegame is largely about whether the bad bishop can be saved or whether Black accepts living with it for the rest of the game.

The same principle works in reverse. A bishop on a long open diagonal, with the player’s own pawns on the opposite color, is among the most powerful pieces in chess. The bishop on g2 in many fianchetto systems is an extreme example of a good bishop.

The bad bishop is not necessarily lost — it can be activated by a pawn break that opens its diagonal, or it can be traded for an enemy piece of comparable value. Bad bishops that survive the middlegame can become assets in the endgame, where their defensive properties matter more than their mobility.