Yvonne Ortega asked an excellent question about using sidebars and endnotes.
You’ve probably seen courtroom dramas on TV where the judge calls both lawyers upfront and to the side so that the jury can’t hear. That’s where we get the term sidebar.
In writing, a sidebar is a short article, usually boxed or shaded, that provides readers with additional or explanatory material. Some publishers put sidebars on a separate page, and others insert it into the text.
I wrote a book for Dr. Jan Kuzma called Live 10 Healthy Years Longer in which we used several sidebars. One chapter called “Just Another Drink” dealt with caffeine. Dr. Kuzma’s point was that there are no positive effects of caffeine (except a temporary high), and he pointed out a dozen negative effects. We put in a sidebar titled “How Much Caffeine?” and listed the amounts in various soft drinks and candy bars. Nice information, but it wasn’t essential to the chapter.
Endnotes are, of course, footnotes, but their designation tells you where you place them—at the bottom of each page or at the end of each chapter (or more regularly at the end of the book).
Twila Belk and I wrote I Believe in Healing with seven pages of endnotes. Seven pages means a lot of interference with the text, so endnotes seemed the obvious answer. Almost all the 59 endnotes were references on where we got the material, and most readers wouldn’t care.
By contrast, I wrote Stolen: The True Story of a Sex Trafficking Survivor for Katariina Rosenblatt for the same publisher and used footnotes. The reason was twofold. First, there were few of them, less than 10 in the entire book. Second, they contained information pertinent to the material.
I think of a footnote as a brief kind of sidebar. It’s significant enough to include for readers on the page, but if you insert it within the text it’s disruptive and disjointed.