Anatomy of a book page

A printed page has about twenty named parts, and knowing them turns a vague feeling that a page looks wrong into a specific thing you can fix. Most of the words below also appear in your printer's error messages.

The page itself

Trim size	The finished dimensions after the paper is cut. 6 by 9 inches is the self-publishing default.
Recto	The right hand page. Always odd numbered.
Verso	The left hand page. Always even numbered.
Spread	The two facing pages a reader actually sees. Design for the spread, not the page.
Bleed	Artwork extending past the trim so no white edge shows if the cut drifts. Usually 0.125 in.
Safe area	The zone inside the trim where nothing will be cut off. Keep text out of the margins.

The margins

Gutter, or inner margin	The edge nearest the spine. Wider than the outer margin, and wider still on a thick book.
Fore-edge, or outer margin	The edge you hold. Where a thumb goes, so it needs room.
Head margin	The space above the text block.
Foot margin	The space below it, usually the largest of the four.
Text block	Everything inside the margins. Its shape is the single biggest decision on the page.

What sits in the margins

Running head	The line at the top carrying the author on the verso and the title on the recto, or the chapter.
Running foot	The same thing at the bottom. Pick one, not both.
Folio	The page number. That is all the word means.
Dropped folio	A page number at the foot when the running head is at the top.
Blind folio	A page whose number is counted but not printed. Chapter openings and blanks get one.

The type

Measure	The line length. Aim for 60 to 70 characters. Shorter and the eye jumps back too often, longer and it loses the return.
Leading	The distance between baselines. Named after the strips of lead that used to create it. About 1.3 times the type size.
Baseline grid	The invisible ruled lines the text sits on, so facing pages line up.
Rag	The uneven edge of unjustified text. A good rag has no obvious shape in it.
River	A pale channel of word spaces running down a justified column. A sign the measure is too narrow.
Drop cap	An enlarged opening letter set into the first few lines of a chapter.

The faults that get flagged

Widow	The last line of a paragraph alone at the top of a page.
Orphan	The first line of a paragraph alone at the bottom of a page.
Stack	Hyphens or identical words repeating down the same position on consecutive lines.
Loose line	A justified line stretched so wide the word spaces show.

Held together

Signature	A sheet folded into a group of pages. Perfect bound paperbacks work in multiples of four.
Perfect binding	Pages glued to a wrapped cover. What almost every paperback is.
Case binding	Pages sewn into boards. A hardcover.
Colophon	A note at the back naming the typeface, the paper and the printer.

Which of these a reader actually notices

Almost none of them, by name. They notice a page that is tiring to read, and the usual causes are a measure that is too long, leading that is too tight, and a gutter that makes them fight the spine. Those three carry most of the difference between a book that reads well and one that does not.

Galley sets all of this from the trim you pick, including the gutter widening with the page count, so the defaults are already the conventions above. See book design, or the publishing glossary for the terms in full.

For reference, not instruction. Publishers, agencies and competitions each keep their own house style, and their guidelines win over anything on this page. Written in August 2026. Whichever you pick, apply it to the whole book.

Questions

What is a recto and a verso?

Recto is the right hand page, verso is the left. Recto pages carry odd numbers, verso pages carry even ones, and that never changes. It is why chapters that open on a recto sometimes leave a blank verso behind them, and why your page count moves in twos.

What is the gutter?

The inner margin, the part that disappears into the spine when the book is bound. It has to be wider than the outer margin or the text near the spine becomes hard to read, and the thicker the book the wider it needs to be.

What is a widow and what is an orphan?

A widow is the last line of a paragraph stranded alone at the top of a page. An orphan is the first line of a paragraph stranded alone at the bottom. Both look like mistakes because they are, and typesetting software fixes them by pushing or pulling a line.

Why do some pages have no page number?

A blind folio is a page whose number is counted but not printed. Chapter opening pages, blank pages and full-page images usually get one, because a number floating under a chapter title looks wrong. The number still exists, it just is not shown.

Trim size comparisonThe decision every part of this page hangs off. Spine width calculatorThe gutter's other half. Proofreading marksHow a proofreader points at any of these. Copyright page generatorThe verso that carries the rights and the ISBNs.

More at the resources index.

Knowing the rule is one thing. Galley applies it across the whole book.

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