It’s probably the single most despised document you might be asked to prepare: the synopsis. The synopsis is sometimes required because an agent or publisher wants to see, from beginning to end, what happens in your story. Thus, the synopsis must convey a book’s entire narrative arc. It shows what happens and who changes, and it has to reveal the ending.
Don’t confuse the synopsis with sales copy—the kind of material that might appear on your back cover or in an Amazon description. You’re not writing a punchy marketing piece for readers that builds excitement. It’s not an editorial about your book.
Unfortunately, there is no single “right” way to write a synopsis. You’ll find conflicting advice about the appropriate length, which makes it rather confusing territory for new writers especially. However, I recommend keeping it short, or at least starting short. Write a one-page synopsis—about 500-600 words, single spaced—and use that as your default, unless the submission guidelines ask for something longer. If your synopsis runs longer, anything up to two pages (again, single spaced) is usually acceptable. Most agents/editors will not be interested in a synopsis longer than a few pages.
While this post is geared toward writers of fiction, the same principles can be applied to memoir and other narrative nonfiction works.