Movies with open endings are the type of movies where you don't get a specific ending, rather it ends with you interpreting it whichever way you want to. Let's take a romance movie for example, after they have gone through many separation and obstacles, it ends with the couple smiling and looking at each other, while the ending does not show them come back together but we can interpret it that way. Personally i am not a fan of open endings, i prefer closed ones, where the writer tells us how it ends.