The Queen’s Gambit declined as black is my specialty. After playing 1 d4…d5 2 c4, you can play dxc4 which is met with Nf3, e4 or e3 or you can play e6 which is the Queen’s Gambit Declined. You can also play the defense c6 which is moving into the Semi-Slav defense in which black pushes both c6 and e6. in the Slav defense only c6 is pushed. My variation for both sides is 1 d4…d5 2 c4…c6 3 Nc3…e6 4 Bf4…Nf6 5 Nf3…Nbd7 6 g3…Bb4 (pining knight) 7 a3 (or Qb3 which is not quite as good due to premature Queen development (if Bd2 then …Bd6 grabs the important b8-h2 and a3-f8 diagonals)) 7…Be7 8 Bg2…0-0 9 0-0…Qa5 10 Ne5…Nxe5 11 Bxe5…Ng4 12 Bf4…dxc4. The combination that white did, g3 and then Bg2, is called a Fianchetto . Fianchettoing is generally a good thing as it allows you to castle, in this case it is Kingside. Castling Queenside is not as ideal because it leaves the king in a slightly dangerous position if you don’t move him to the b-file. In most pawn structures, after a series of pawn exchanges, the c file is often left open. Castling Queenside leaves the King on that weak rank.