One huge advantage for authors about Google Book Search is it enables people to discover your book, even if they weren't necessarily looking for a book. If a Google.com user searches for words that appear in your title or text, a link to your book can be displayed above the regular Web-page results. This can lead to dozens or hundreds more people stumbling onto your book daily.
Like Amazon's Search Inside program, Google Book Search gives free access to your book's complete table of contents and index. In response, savvy nonfiction publishers these days are printing tables of contents with as much detail as possible, making them more attractive to browsers. For example, instead of a brief table showing only chapter headings, the table mentions every section and subsection, nearly down to the paragraph level. The more information you can pack into your table of contents, the more likely you can hook a reader who's begun skimming it online. Content tables should read like a high-end restaurant menu, artfully mentioning every essential ingredient and whetting the reader's appetite.
Google runs small advertisements from its AdWords network on the Book Search pages, and splits the ad revenue with publishers. When someone clicks on an ad from a page displaying your book, you get paid, although publishers agree that revenue from the program has been minimal.
Safeguards are built into Google Book Search, similar to Amazon's Search Inside the Book. Users can view a limited number of pages of a low-resolution image of pages that can't be printed easily or saved. A portion of the book is kept offline so users wouldn't be able to see the whole book even if they had several different Google accounts.
A separate project, Google Library, is often confused with Google Book Search. The program is digitizing millions of books from six leading public and university library partners. The Library program has been controversial among many publishers because Google isn't asking for permission of rights holders before scanning the books.