Backstory, or background as it is sometimes called, is all that wonderful knowledge you, the author, have come up with for character or storyline details. It gives depth to the characters. It adds depth to settings and bulk to the storyline.
Too much backstory or too little backstory can also drive a reader away from the story. Understanding exactly what to reveal, when to reveal something, and why it needs to be revealed can be tricky.
Understanding the proper amount of research the author has learned about settings, time periods, etc. to include in a story is a similar problem. In both instances, it is easy for a writer to give the reader an information overload. Often you need to get the story fully written and then go back in your revision process and dig out those areas of informational dumping. But I’ll go into that subject at a later date.
As always, the Backstory: Purposes & Problems article has been added to both the Writing Tips on this blog and to the Writing Tools on my website.