FIANCETTO

hi guys! i'm a novice..i played an opponent who likes playing a fiancetto..i bet him but i'm still wondering what's that purpose of that opening?what is the weakness?how to properly  depend and attack it?

First fianchetto is not an opening, but some openings involve it. Second it's a strong move, on the king side as well because it makes a very strong defense and the bishop has not only the longest diagonal, but also attacks the center. Openings involving a fianchetto are usually very solid and quite strong. I don't think there is any "method" for countering a fianchetto as it is mostly a positional move, however if let's say white fianchetto his dark bishop, then you may try blocking his bishop with preferably one of white's own pawn or by one of your pawn, but you have to be careful that it's carefully defended. Also, while the bishop will have a good position, it is not very mobile so your own dark bishop may try controlling other important dark squares and causing troubles in dark diagonals where the fianchettoed dark bishop don't have access.

But of course, it all depends on the position... but you shouldn't worry too much about a fianhettoed bishop, the bishop is strong, however it does give you some tempo as it takes two moves to get it there, so while it's strong it usually doesn't give the player any significant advantage (but again, it always depend on the position) it's mostly just a different way of positionning your pieces.