The Moon has a far side (a side that is always facing away from earth) but has no dark side. As the moon passes between us and the sun the far side is bright side. As the Moon goes around the other side, the near side is the bright side (and we see it in the sky).
As the far side has generally been more exposed to objects from deep space it is also the more rugged of the two sides.
The title of this post is from the end of the Pink Floyd album Dark Side of the Moon. At the end of it, the doorman to Abbey Road studios says “There is no dark side of the moon, really. As a matter of fact it is all dark.” He’s talking about the lack of an atmosphere, presumably. But what a great way to end that album.