This book addresses the underlying foundational elements, both theoretical and methodological, of sponsored search. As such, the contents are less affected by the ever-changing implementation aspects of technology. Rather than focusing on the how, this book examines what causes the how. Why do certain keywords work, while others do not? Why does that ad work well, when others that are similar do not? Why does a key phrase cost a given amount? Why do we measure what we do in keyword advertising? This book speaks to that curiosity to understand why we do what we do in sponsored search. The content flows through the major components of any sponsored search effort, regardless of the underlying technology or client or product. The book addresses keywords, ads, consumers, pricing, competitors, analytics, branding, marketing and advertising, integrating these separate components into an incorporated whole. The focus is on the critical elements, with ample illustrations and with enough detail to lead the interested reader to further inquiry.