When our formatters lay out your book's interior, they generally set the formatting so paragraph options have two rows at the end of a page and at the start of a page. This formatting style avoids a line or word of text that jumps to the next page/column or starts a page/column, can call more attention to the unintentional white space, and be distracting. This industry standard, common formatting practice can result in uneven bottom margins on some facing pages if they would result in only one row at the end of a page or the start of a page.

Two examples, with explanations, are below. 

If you do not prefer potential uneven last lines on a page, rest assured we will change the formatting. However, the new formatting that keeps bottom lines of facing pages even, can result in "orphans and widows" on a number of pages.

What is an Orphan? 

A paragraph-opening line that appears by itself at the bottom of a page or column, thus separated from the rest of the text. (They have no past but a future.)

What is a Widow?

A paragraph-ending line that falls at the beginning of the following page or column, thus separated from the rest of the text. (They have a past but no future.)

Please see below for an example of a widow and orphan. 

Rest assured, no matter your formatting preferences, we will continue to work to create the best possible book for you.