Why does the Moon always show us the same face?
It's not that the Moon doesn't spin — it spins exactly the right amount.
1However long you watch, the Moon always shows Earth the same face; its far side went unphotographed until a probe imaged it in 1959. The reason is not that the Moon doesn't rotate — it spins once in about 27.3 days, exactly the time it takes to orbit Earth once.
2This synchrony is called tidal locking, and it is no coincidence: Earth's gravity slowly braked the Moon's spin over billions of years until rotation and orbit locked together. The Moon's gravity is doing the same to us — a day on early Earth lasted only a few hours.
3The far side is therefore not a 'dark side' — it gets day and night just the same. It is simply a face Earth never sees.
Tidal locking — rotation and orbit in step — keeps one face of the Moon toward Earth.