You have an outline. You’ve checked out the competition. It’s time to explain why your book is needed now. Perhaps you haven’t even considered this question before today.
But publishers will want to know. If you’re writing about an area in which you have expertise, you should be able to come up with a good answer. Put together some industry stats. If you’re writing a book about small business, visit the SBA site, where you’ll find all kinds of useful numbers, such as how many small businesses exist today, and how many fail. Why do they fail? Would your book help entrepreneurs better run their business? Are you including proven tips for success in today’s economy, and in an easy-to-digest format?
That’s the kind of information to put in your proposal. The better you can articulate the case for your book, the stronger the proposal.