Extract from an article from YA Buccaneers site:
A couple of weekends ago, I was lucky enough to attend a full-day plot workshop by editor Cheryl Klein. It was super informative–Ms. Klein passed on a ton of helpful information. Before the class, we had been given two homework assignments. One was to read a novel that she’d use as an plotting example during the workshop. The other was to create a book map. This, and the subsequent exercises Ms. Klein had us do with our maps, was by far the most helpful aspect of the day.
What’s a Book Map?
In a nutshell, it’s an scene-by-scene outline, created either in an excel spreadsheet using columns, or as a list in a word document. It’s used to track various elements of your plot, like each scene’s conflict, where characters appear, etc. You can use it to track whatever you’d like.
Now, don’t fret if you aren’t the outlining type. It doesn’t matter if you’re a plotter, pantser, or both. This isn’t an outline that you use to write your first draft. You use the map to check the plot you’ve already written. So, you shouldn’t create a book map until after your first draft is complete.