If both Earth and Moon are rotating as well as revolving around some focus, shouldn't they have drifted out of phase with each other long ago? So, why do we always see the same side always?
The moon always poses the same face to the earth because its rotation period around its axis is equal to its revolution period around the earth. It is this way due to tidal locking. See: https://en.wikipedia.org/wiki/Tidal_locking