Space advantage
How to quickly illustrate the concept of space advantage? Try this opening, an irregular Alekhine:
1.d4 Nc6!? 2.e4 Nf6?! 3.e5 Nd5 4.c4 Ndb4
If instead 4…Nb6 then 5.d5! Nxe5 6.d5 Nbc4 7.Qd4 wins material.
5.a3 Na6 6.b4! Nab8 7.f4!
And the result of Black’s naive knight maneuvers? Black’s g8-knight has swapped spots with his easterly cousin, and White has not yet developed a single piece. Yet White maintains a clear advantage due to his greater command of the board.