Catalan - open - classical line
1. d4 Nf6 2. c4 e6 3. g3 d5 4. Bg2 dxc4 5. Nf3 Be7
White moves the queen's pawn to d4. Black develops the knight to f6. White moves the c-pawn to c4.
Black plays the king's pawn to e6. White plays the g-pawn to g3. Black plays the queen's pawn to d5.
White develops the light-squared bishop to g2. Black captures on c4 with the queen's pawn. White develops the knight to f3.
Black develops the dark-squared bishop to e7.