  A change is real if and only if it makes on its own a real difference to the world. Real change is (roughly) change involved in causing something, change an item is caused to undergo or change not “logically parasitic” on change in other things. (These “or”s are inclusive, not exclusive — one change can satisfy more than one clause of this account.) Smith's kicking me involves changes in Smith. Kicking me makes on its own a real difference in Smith. When Smith kicks me, I undergo various changes which count as real, intuitively — being kicked makes many real differences in me. On the other hand, when I become shorter than Smith because Smith grows, Smith changes really but I do not. Gaining height makes a real difference in Smith, but Smith's gaining height doesn't make a real difference in me. Rather, my becoming shorter than Smith in this way is logically parasitic on Smith's growing. It is simply a logical consequence of a real change in something else, not a real change itself.