Sacrificing Bishops early?

I have been a bit confused by a move that I run into often. I see this move frequently, especially if I am using a King's or Queen's Gambit. In some ways I get it. It can break up the King's side offense that I am trying to build. It also pins the knight due to the potential attack on the king or queen (depending if I am playing white or black).

Is this a wise sacrifice of the bishop for my opponent? What might be some defensive suggestions so I can avoid this and keep my King's side offenseive?

Hello.

What I've seen most of the people do is taking the bishop with queen or bishop instead of pawn, so that they can develop another piece and attack better from king side.... *its just something I've seen lots of people do*

This is not a sacrifice, but an exchange / piece trade (bishop vs. knight) - and I'd say gxf6 is a bad move here, the way to go is Qxf6 - f6 is a rather strong place for the queen as soon as the black-squared bishop is gone, and the pawn structure remains intact.