A book proposal is a simple proposal format that is used to sell nonfiction books to publishers. It shows why your book is a saleable and marketable product. The book proposal act as a business plan that convinced the publisher to make an investment in your book.
In a novel, the entire book is written first, then trying to find an editor or publisher. In the case of a nonfiction book, the book proposal in written first before you write the whole book. If your book proposal template convinces the publisher, then they will contract and pay you to write the book.
Here are the tips in writing a book proposal that the publisher would actually read.