Obviously when you hear about successful novel series you think of the big three: Harry Potter, Twilight, and the Hunger Games. Of course there are TONS of them and I don't doubt that there will be more novels series that are turned into movies (cause they are awesome).
But if your thinking about making your own novel into a series, it's not always crystal clear as to whether it's meant to be a stand alone or series.
What's your favorite series that you're read? What was it that you liked so much?