Annotated by yellowlab (2033): 1. d4 is the second most popular opening choice for white. It occupies one center square and attacks another (e5). It opens a line for the bishop on c1, and offers a slight boost to the queen's mobility. The d2 square is now an option for the knight on b1 as well. There is a slight weakening of the e4 and c4 squares, because the d-pawn can never be used to help control them. A flexible move. …
