I recently received this statement from my sister:

"I told Mike [her son] that the moon revolves, and he said it didn't, because the face was always toward the earth. I said if it didn't revolve, as it goes around the earth we would see the back side of the moon. He went online and asked the question, and got quite a few responses, all of them saying "Your mother is right."

Is my sister really right?

Thanks for help in advance. I'm not receiving my notifications so it may be a day or two before I read the replies.

If by "dark side" you mean a side that never sees the Sun, no. If by "dark side" you mean a side that never sees the Earth, yes.

The Moon rotates once per orbit, so it is putting almost the same face to us at all times. Think of it as driving around a circle - the same side of the car is always facing the center of the circle, but the car goes through a full circle of directions (i.e. it rotates once).

The reason has to do with the water on the Earth moving around with the Moon. The gravitational interactions end up forcing the Moon to keep the same face to us.

It's not completely true that the same part of the moon faces us at all times. The moon follws an elliptical path, which screws up the synchronization somewhat. Still, almost half of the moon never faces the Earth.