I don't know why but I always thought the moon spun on its axis the same way the earth does and as such thought "the far side of the moon" meant "the side not facing the earth at that particular time......."
You learn something new every day.....basically the moon has a "bump" and because of gravitation that bump faces us permanently.
Its a little biit more complicated than that as the moon "IS" spinning on its axis but because of how we are spinning its still always facing earth.
even harder to understand we are actually seeing about 59% of the moon because of the "rocking" motion or speeding up and slowing down which has a technical term called "libration"
So there really is a far side of the moon......and if you were there you couldn't use radio to talk to people back on earth....
Some more explanations can be found at http://earthsky.org/space/five-myths-about-the-moon#moon-gravity