The Bible tells us that to be pure, you must look after widows and orphans. The same is true of typesetting a book. In order to have a professional looking interior, you must take care to avoid widows and orphans.

In typesetting terms, a widow occurs when the last line of a paragraph ends up on the top next page, leaving it widowed from the rest of the paragraph. An orphan is when the first line of a paragraph sits lonely and forlorn at the bottom of one page while the rest of the paragraph continues on the next.

A common way to remember this is to think of the phrase, "an orphan has no past, a widow has no future."

When you're going through your typeset book looking for widows and orphans, here are some things you should, and should not do.

1) Always start at the beginning of the book when fixing paragraphs. If you start at the end, each new fix you make will cause a problem for each fix you've made before.

2) Never adjust the line spacing of a page of full text. It is very noticeable and unsightly in the finished book, and should be avoided at all cost. The only places it is acceptable to adjust line spacing by a few points is around images and subheadings, and those should be changed only as a matter of last resort.

3) Never adjust the left and right margins of a page. Unless you're using really thick stock, this is something that the reader will notice through the page. It gives your book a feeling of "cheapness" when the margins vary from page to page.

4) Do adjust page lengths, if required. If necessary, you can start a few pages back from the widowed line to eliminate the problem. Common practice is to allow for any page to be one or two lines "short" or one line "long" to eliminate widows and orphans.

5) If your layout requires each page to be exactly the same length, and all other solutions fail, the only thing left to do is to edit your text to remove or add a few words.

Book layout and interior design is often a long and tedious process, and if possible, should be left to those who specialize it the process. But if you need to do it yourself, take the time and effort to make your finished product as professional as you possibly can.