A widow is a single line of a paragraph stranded at the top of a page. An orphan is a single line stranded at the bottom. Both break the reading flow and signal unprofessional formatting. Every professional typesetter eliminates them; they require manual adjustment of tracking, spacing, and page breaks throughout the manuscript.

Interior margins (the gutter toward the spine) must be wider than the exterior margins to compensate for the binding's space requirements. Too narrow, and the text disappears into the spine. Too wide, and the book looks amateurish. Gutter width is calculated from page count and binding type, not guessed.

Chapters in traditionally published books always begin on a recto (right-hand, odd-numbered) page. When a chapter ends on a recto page, the following verso (left-hand) page is left intentionally blank. This is a deep-seated convention that readers feel, even if they can't name it. Violating it signals a book that wasn't properly typeset.

The body typeface must be a text-optimized face designed for long reading, not a display font or a common system font. The right typeface at the right size and leading creates a reading experience so natural that the reader never thinks about it. The wrong choice creates micro-fatigue over hundreds of pages.

Running headers (the text that appears at the top of every page, showing the book title and chapter title) must follow a specific convention: the book title on verso pages and the chapter title on recto pages. Page numbers (folios) are consistently placed and styled, suppressed on chapter-opening and blank pages per typesetting convention.

The first paragraph of every chapter is formatted differently: no indent, optional drop cap, and possible space before the first line of body text. These small distinctions signal to the reader that a new section is beginning and lend the book a sense of completion. Inconsistent or absent chapter opener treatment is immediately noticeable.