Once a Upon Time... 

   "Long before books were made, people told stories. They told them to one another and to the children as they sat before the fire. Many of these stories were about interesting people, but most of them were about the ways of fairies and giants.
    In those days, if people did not know why strange things happened, they said it was because of fairies. Even then, they could imagine such wonderful things that fairies might do. Of course, the people who told the stories in that long ago time, and the people who listened to the stories, really believed in fairies.
    At the same time, these are about people, too. The people in the stories are often so real that you imagine you might be in their place, or that we might know them in real life.  Most of the fairy stories also have some lesson that we might learn and thus be a wiser person".             Dolch and Jackson  

When fairy tales were first published, publisher believed that children would not read the books so fairies were added to the cover.  Mailbox

  What is a Fairy Tale?

An interesting but highly implausible story; often told as an excuse  
A story about fairies; told to amuse children.
Fairy Tales are actually folktales containing magic and supernatural elements that convey lessons of morality.

A fairy tale is a story, usually told to children, concerning the adventures of mythical characters such as: fairies, goblins, elves, trolls, giants and others. Also, it often involves princes and princesses. American fairy tales normally have a happy ending, but German and other European tales most often have a bad ending (e.g., a girl plays with matches and burns the house to the ground)

What Makes A Fairy Tale?