The Web is a complex self-organized system whose evolution and use is shaped by many concurrent social, cognitive, economic, and information phenomena. This tutorial will describe ongoing efforts to study the topological and dynamical properties of link, content, and semantic networks stemming from some of these forces. We will discuss what we think, what we know, what we can use regarding the structure, content, and use of the Web, and what the future of intelligent, cooperative Web search may bring.