Publishing a book is one of the best ways to position yourself as an expert in your field. Not only that but the book demonstrates your expertise in its best and most organized format. And perhaps the biggest advantage of all is that your book allows people to be introduced to your expertise without you doing a thing. Yes, you have to write it and get it published. And you also have to market it. But after that, you can sit back and let people read it on their own time.