Introduction; Part I. Shapeless Networks: 1. Galton-Watson branching processes; 2. Reed-Frost epidemics and Erdős-Rényi random graphs; 3. Connectivity and Poisson approximation; 4. Diameter of Erdős-Rényi graphs; 5. From microscopic to macroscopic dynamics; Part II. Structured Networks: 6. The small-world phenomenon; 7. Power laws via preferential attachment; 8. Epidemics on general graphs; 9. Viral marketing and optimised epidemics; References; Index.