fredthebear: Space advantages are created by advancing pawns to the frontier line, and beyond. Since pawns cannot go backwards, it's a permanent fixture. A space advantage gives one more room for his pieces to operate. In fact, if one's pieces are unable to operate there, one probably should not advance his pawns there. Once the pawns take off, they can never return home; it's a permanent leave.
The farther the pawns march toward the opposing camp, the more difficult it gets to protect them from behind. However, a phalanx of pawns charging forward threaten to capture or cramp everything they come in touch with. It takes time (costs multiple moves) to get slow pawns down the board!
Advancing pawns also leave weak squares behind and beside the pawn, because those squares can never again be defended by a pawn (essentially one is moving the wall of the fort, expanding it like a balloon). You don't want the opposing army to penetrate between/behind your pawn structure.
Thus, pawn advances are highly committal; it can be a strength and/or a weakness.
One can win games without a space advantage by constantly moving your pieces (not pawns). The quickest versions of Scholar's Mate, for example (1.e4 e5 2.Bc4 Bc5 3.Qh5?! Nf6?? 4.Qxf7# 1-0), White only moves one pawn and two pieces; the pieces fixate to deliver checkmate. Against an alert opponent, an army must move at least two pawns in the opening to allow both bishops and the queen off the back row. Bishops prefer to be in front of their pawns, not behind their pawns.
It is especially dangerous to move the f-pawn and/or g-pawn without knowing the exact theory of an opening, as the king is exposed to checks on the diagonal. Chess is a battle over control of the center, by aiming into the center, so that the center can be occupied sooner or later. If one wishes to play on the wing, he must neutralize/close the center.
If this explanation was not clear, I would advise studying WEAK SQUARES, WEAK PAWNS, & PAWN STORMS/PAWN ROLLERS.