Evaluating which piece fits the board structure better.
Why it matters
Neither piece is better in general. The structure decides: a knight wants a fixed square it cannot be chased from, and a bishop wants open diagonals and pawns that can still move.
The practical skill is knowing which one you have. When the position is locked, keep the knight and trade the bishop; when it opens, do the reverse, and be willing to trade the piece everyone calls stronger.
See it on a board
The knight on c5 is protected by a pawn, and no black pawn can ever attack it. The bishop on g7 has a long diagonal that runs into its own pawn structure.
Checked: the position really has the feature described.
How to play it
- Ask whether the pawn structure is fixed or fluid.
- Fixed and full of holes: the knight is better, so trade bishops for knights on your terms.
- Open, with pawns on both wings: the bishop is better, and the side with two bishops should open lines further.
At each level
The same idea, said the way it is taught at each age.
Rook · ages 6–9
Count the fixed pawns before trading. A knight with a permanent square beats a bishop that is staring at a wall.
Queen · ages 8–11
The two bishops are worth about half a pawn on their own, and much more once the position opens. That is the real reason to avoid giving them up cheaply.
What goes wrong
- Trading a knight for a bishop automatically, because bishops are 'worth more'.
- Keeping the bishop pair in a completely locked position where the knights have all the squares.
Questions people ask
- When are two bishops strongest?
- In open positions with pawns on both wings, where they cover both colours and cannot be blocked. In a closed centre they are often the weaker pair.