Attack or Defense?

I've heard of people that say "don't move the pawns, move the major pieces into the center", but also "pushing the pawns is the most important, save the major pieces for later attack". So… Which?

Depends on stlye. Hypermodern or "normal".

Pawn play and pieces play are connected. Pawns determine the "landscape" of the chess battlefield, because they are relatively static, and pieces should be played in a way that takes the pawn structure in consideration. When moving the pawns, you create places where it's appropriate to place your own pieces later (by defending them, opening a way, etc), or to prevent the opponent from access to certain spots.

If the current pawn structure favors you, you should attack (or defend) with the pieces, if you don't like it - you should search for a pawn break that will eventually change it into a more favorable one.

GM Andrew Slotis has written a book "Pawn Structure Chess", which includes interesting analysis of different pawn structures and what piece play is appropriate to them (and what strategy in general).

AlexZhang001:

The overiding principle is simply the following:

Winning chess is the strategically and tactically correct advance of the pawn mass.

Pawns are the only piece that cannot move backwards.  Therefore it is critically important that they be advanced only when the strategic and tactical factors in the position call for it.

Recommended reading:  Pawn Power In Chess, by Hans Kmoch