I am putting the final touches on my new novel and thinking about what I should say about it on the flap copy or its equivalent. Flap copy are the words on the inside of a hard-back book's jacket. Publishers craft them carefully to interest book browsers; they are a sales tool, designed to sell the book.
Here, from a book plucked from my shelf, is a good example: "In Vex, Hex, Smash, Smooch, Constance Hale, the best-selling author of Sin and Syntax, spells out exactly what we need to know about verbs to write with confidence and panache. Combining the wit of Bill Bryson with the practical wisdom of William Zinsser, she synthesizes the pedagogical and the popular, the scholarly and the scandalous, to break down our most misunderstood part of speech...." This says: if you care about verbs, this is a book for you.
Paperback books of course do not generally have jackets, so the flap copy has to go on the cover itself and almost always on the back cover where it serves the same function—buy this terrific book. a A browser cannot pick up an e-book, however, scan the back cover, and absorb the sales message. As a result, we are seeing more and more book in which the first page behind the cover is the equivalent of the flap copy: what the book is about, who wrote it; and why you should be interested.
I usually do not read novel flap copy whether on the jacket or on the back cover or on the first page because too often it is either wrong—almost as if written for another book entirely—or because it tells me too much, or both. I want to be taken by surprise and delighted by the story and characters the author has worked so hard to create. I don't want to know before I start that the cask of Amotillado is a ruse to lure Fortunato to his death by being walled up in the wine cellar.
So there's my problem: how much should I say about the new novel? Too much and it spoils the story's effect. Too little and prospective readers have no idea what the book is about. I'm working on it.