Why does the face of the moon 'sync' with the earth?
It is called "Tidal locking", or "gravitational locking" or "captured rotation". According the the Wikipedia page on "tidal locking" (check the references for sources), it is due to Earth's gravity causing a small tidal bulge on the Moon, which affects its rotation. Over time, the Moon's rotation, affect by Earth's gravity, makes it's orbital rotation synchronise with its lunar rotation.