Fianchetto

A fianchetto is a specific way to develop a bishop. White advances the b-pawn or g-pawn and places the bishop behind it on b2 or g2. Black does the same on b7 or g7. From there, the bishop points along a long diagonal that may cross much of the board.

A fianchetto helps fight for the center from a distance. A bishop on g2, for example, can pressure d5 and other diagonal squares without a white pawn first occupying the center. It is also a common developing move in openings that seek a flexible pawn structure.

When the king castles on the same wing, the bishop often helps protect nearby squares. It does not create an invulnerable fortress, however. If the bishop is exchanged or leaves the diagonal, squares of the color it controlled may become harder to defend. Its own pawns or pieces can also block it.

The bishop's value depends on whether the diagonal can open. It may look passive for several moves, but a central pawn exchange can turn its diagonal into an open line and immediately increase its range. The whole diagonal matters, not only the squares nearest the bishop.