Book sales in the United States exceeded $27 billion in 2011, according to a report from the Book Industry Study Group. That doesn't even include sales of self-published and vanity published books. Despite the big market, getting a book published is not easy. If you want your book sold in book stores and other retailers, you will need to go through an established publisher. To do that, it's important to be aware of how the industry operates.

Fiction

Publishers rarely contract for an unwritten novel from a new author. The entire manuscript must be completed before you start looking for a publisher or agent. Compose a book blurb to entice the publisher or agent to read the entire cover letter. Practice by reading back-cover blurbs from well-known authors. Send the cover letter, a one-page synopsis of the novel, and your writing credits to the publisher or agent. If an agent or publisher is interested, they will most likely ask to read the first 50 pages or three chapters of your novel.

Nonfiction

Authors of nonfiction books are often offered a contract before they're completed the book. If you have written a nonfiction book, evelop a chapter outline with a descriptive paragraph for each chapter. You will also need a sample chapter. Select a chapter that you're particularly excited about to write. It doesn't have to be the first chapter.

Compose a book proposal. This includes a summary of what makes your nonfiction book stand out from the field. Include your qualifications to write the book. List recently published books that compete with your book, and explain why your book is better. Describe who would read your book and how you will promote the book to the readers. Include marketing strategies that your publisher could use to promote the book.

Package the book proposal with the book outline and sample chapter along with a cover letter and send to the agents or publishers you've selected.

Agent or Publisher

Literary agents get paid when they sell the book to a publisher. Their compensation is a percentage of the total advance to the writer. Most agents require no upfront payment from the authors they represent. Besides knowing which publisher is looking for what kind of book, literary agents also review the publishing contract for the author.

Nearly all major fiction publishers only accept manuscripts from literary agents. The publishers look at the agents as a vetting mechanism to weed out the tired, clichéd and poorly-written books. Publishers of nonfiction books will accept book proposals directly from writers. Find agents or publishers who represent or publish your type of work. It's not productive to send a romance book to an agent who only represents business nonfiction books.

Payment

Publishers pay authors through an advance and royalties. The royalty is a percentage of the sales a publisher receives for the book from wholesalers and distributors. The advance is a lump sum figure based on what the publisher thinks the book will sell in the first two years after publication. For example, if the publisher pays a 10 percent royalty on net sales and believes the book will sell 5,000 copies at $8 per copy, the sales would total $40,000 and the advance would be $4,000. Unless the author's contract specifically states that the royalty must be paid back, it doesn't have to be if the sales don't reach what the publisher projected.