There is a distinct feeling that a page doesn’t quite work without even reading a word. The words may be easy to understand, the typeface may work well, the chapter name may be centered, and yet the whole page looks bad. Often, the fault is not with the typeface or the design; it is the margins. Margins determine whether a book looks spacious or cramped; balanced or off-balance.
Margins aren’t just the area leftover after the type is set. The space of white between the type and the page boundary defines where the reading area begins. It protects the reader’s eye from the edge of the page, and gives the text breathing room. The inner margin also has to accommodate the gutter space where the two pages join into the spine; without enough of a margin, the gutter may become a problem in its own right; without the gutter, there is enough of a margin for the eye, words may appear to be swallowed by the spine on close inspection; without the outer margin the page appears to have no space, and to have no reason to look like a page at all.
For the beginning designer, it is tempting to make the margins as narrow as possible, in order to fit as much type as possible onto the page. However, this will not solve all of the book’s design problems; in fact, this may create more problems. The type will run off the page; and the page may become too full for the eye to be comfortable on. The page should not look like a page that has been filled to the edge, but one that has been given room for the eye to breathe.
The book interior is not simply a container for words; the page is a whole environment into which words must fit. One of the chief mechanisms for creating this design is the margin system.
Here is a test: make a single page spread and a sample text from a new manuscript. Make three versions: one with narrow margins; one with moderate margins; and another with wider margins. Keep the type and line height and paragraph spacing exactly the same for all three versions. Then look at the spread as a whole. Look to see how the block of type looks. How much weight does it hold? In the version with the smallest margins the page will look a bit crowded and inefficient. In the version with the widest margins the page will feel a bit empty, but the text may look a bit too short.
Margins also help to establish hierarchy. The chapter page should have a bit more type space at the top to set it apart as more important. The chapter number should not feel squashed against the type, or against the edge of the page. The running headers and page numbers should not crowd the text, or make it more important than it is. And the captions and images have more white space to breathe without. Without this space, all the parts of the page begin to feel like they want to take over; and it is difficult for the eye to see who is who.
One quick way to test this is to blur your eyes or zoom out of the design. When the type gets too small to read, does the page still look well-defined? Do the left and right pages feel like a whole? Is the gutter still wide enough for its purpose? Are the outside margins feeling less and less nervous as the design widens? It is much easier to spot margin mistakes if you are not trying to read every little line.
It is true that better margins will not create the most beautiful page; but it will make it easier to decide on what is beautiful. There will be more room for the text to settle on the page; the type will become more legible; line length will become a more important design problem; and the page number will not look like an afterthought. It is good practice to check the margin layout before moving on to typefaces and layout; it may seem a minor change, but a few millimeters can make all the difference to the look of the whole design.