The same two leading principles apply to Queen's Pawn openings
which were discussed in connection with the King's Pawn openings;
but there is one great difference between the two kinds of
openings which is not obvious to the beginner. This is the fact
that in Queen's Pawn openings, in most cases, neither player has
a chance to open a file in the center of the board through the
exchange of one of the center-Pawns, and that, therefore, an
additional Pawn move is necessary in the opening stage to provide
for an open file in which the Rooks later on may have an
opportunity of entering the battle.

In addition, it is in most variations not easy to find a good
place for the Queen's Bishop without further Pawn moves, and it
is here where the beginner is bound to err in the plan of his
mobilization unless he has adequate instruction.

In trying to open a file for the Rooks it will be advisable--just
as in the King's Pawn openings--to aim at the same time at the
clearing away of the opponent's center-Pawn, and this can only be
done by the advance of the c-Pawn. Therefore, it would mean loss
of time if the Queen's Knight were developed into the c-file
before the c-Pawn has moved; the Knight would have to be moved
away again in order to enable the opening of the c-file. This
consideration furnishes the key for the understanding of the most
popular Queen's Pawn opening, which is

(1) P-d4 P-d5
(2) Kt-f3 Kt-f6
(3) P-c4