WBEZ brings you fact-based news and information. Sign up for our newsletters to stay up to date on the stories that matter.If you’re running for President, a campaign book is practically a requirement. But why? And what do they actually reveal? This episode: Sam Sanders, campaign reporter; Danielle Kurtzleben, digital political reporter; Ron Elving, editor and correspondent. Find the team on Twitter @nprpolitics and at npr.org/politics.