How is it that no matter where you are on Earth, you can always see the moon?

You cant see the moon all the time. It takes the moon a month to complete one rotation around the Earth. Thats called the Sidereal Period. The word Month comes from "moon". If you see the moon tonight at say 7pm and look tomorrow night at 7pm the moon will be slightly to the east. Often the moon is below the horizon. Some stars you will never see from the northern hemmisphere and vice versa