Though we share much of the same night sky view, there are certain stars only visible from one hemisphere or the other (most easily noticeable to most of us constellations). We see the same sky over a short duration of time, like seasonally, because the earth faces the sun, and thus that way through space, during the day and rotates away from the sun, facing the opposite direction through space, at night so we're facing the same direction, and same piece of the sky, night after night. But, as the earth revolves around the sun, our view of the night sky does change over time. If you begin to take note of the constellations in your view of the night sky, you'll see different constellations come into and leave our view over the course of a year. Still, other stars that remain (how we'd think of it as) "above" the Earth (if you're in the northern hemisphere like me) can be seen year round because they're millions of light years away and their relative position doesn't change much to us and the relatively small orbit we travel. Google sky maps is a great way to start learning about our ever-changing night sky, and there's ton of info online for novice astrologers and star-gazers to get you started. Watch and learn!