The End

What makes an ending "The End"?

In a word: closure.

At the end of the story, whether the heroine won or lost, she's not going to get another chance to try.  The Evil Overlord is gone for good, the wedding is on (or off), the murderer has been discovered and arrested. There may be some loose ends, but the main thing is over and done with…whatever "the main thing" is for that particular story.

In order to achieve this, the story first has to provide a question that needs answering, or a problem...