A fianchetto places the bishop into a very well protected position on the longest diagonal. It is quite difficult to attack such a bishop - the only way is using a bishop of the same square colour.
A fianchetto is also a nice and solid defense for the castled king.
The only real drawback of a fianchetto is that it fixes the pawn structure. If you plan a pawn storm on that wing later on a fianchetto is the wrong set-up.
Cheers, Winnie
People do this to be "cool" or "different."
It's in the spirit of hypermodern chess: Black develops smoothly, trying to control the center with pieces rather than pawns, and he hopes challenging the center later by pawn breaks.
There are two theories of chess:
Classical Chess Theory- Control the center by occupying it with your pawns and pieces.
Hypermodern Chess Theory- Control the center by using the power of your pawns and pieces. With this method you do not create targets for your opponent to attack. This method seeks to use the long range power of the pieces to overwhelm the opponent's pawns and pieces.Only once you have overpowered the enemy's control of the center do you occupy it with your own pawnsand pieces. An example of controlling the center with the power of your pawns is Nimzowitch's 'small but secure center'. The pawns are not targets in the center but their combined power close to the central squares excersizes a strong influence on the center, which when properly coordinated with the power of the pieces, will spring forward in a liberation charge and sieze control of the center from your opponent's pawns and pieces.
Fianchettoing your bishop(s) is in keeping with the Hypermodern Chess Theory.
I played a guy yesterday, he fianchettoed both sides. What's the purpose of the fianchetto? to pull the c pawn out later, to open a long range possibly unseen attack by the bishop? to protect your rook?
Thanks, Davy