Exposition is used in two ways when talking about fiction.
First, it is the set-up at the beginning of the plot arc. Where we learn the basic who, what, when, and where. This is a necessary part of plot to ground your reader.
I'm going to address the second way exposition is used in a story. This is when an author gives background information, description of characters or setting, or summarizes events that have already happened. It can happen at any point in the story. This is a necessary, key element of writing and one of the three tools an author has to tell his or her story, along with scene and dialogue.
A good author does this without slowing down the forward progress of the plot. That is, the exposition makes sense in the context of the scene (or action) of the story and does not trip up the reader or bore him or her.
She turned her blue gaze toward him.Here, we get the fact that she has blue eyes in the context of the action. That's the best way to give description.
One mistake amateur writers make is including "infodumps" in their stories. These are paragraphs of exposition which trip up the reader and slow the forward progress of the plot. They take the reader out of the action. As a result, these infodumps can result in readers setting aside a book and giving up on a story.
|Green Room by Donna McNeely|
Sprinkling in a few relevant details is great, and necessary. It grounds the reader in setting and helps him or her envision the world the author is creating. But these details need to be intrinsic to the plot, and can't stop the forward momentum of the action. Does it really matter, in the grand scheme of the story, that the bedspread is green? Ask yourself that before including the detail in your story.