Open and Closed endings

As human we all have a strong sense of curiosity and hate the unknown, this is why most films will follow a closed ending structure.

Close ending- the story has a well rounded definitive ending, all of the questions around the plot are answered leaving the audiences satisfied 

Opening ending- the story is cut short of this explanation and left to the interpretation of the audience, we do not know the definite ending to the film (unless a sequel explaining this is made)

Open ending admittedly are a lot more impacting and effective on the audience, they make the audience stop and think about the story, themes, and the deeper meaning behind it all. However they are very frustrating and if a sequel isn't planned cause cause a lot of negativity in reviews, on the other hand when a sequel is definitely going forward open endings are almost always used, this is a sure way to get an audience to come back and what the next film.

The narrative, plot and themes to the story usually determine whether a film will be open or closed endings, but at the end of the day it is down to the effect you as the create what to inflict onto your audience. 

However typically the most satisfying method of endings are closed; when there are multiple films being made each should have an open ending but at the final film finish with a closed ending.