Explore the emerging "science of networks" in this comprehensive lecture from the Santa Fe Institute's C4 Public Lectures series. Delve into the interconnected world of technological, biological, and social systems, and discover how mathematical models of random graphs provide insights into real-world network structures and functions. Examine phase transitions in networks, where small environmental changes can dramatically alter network structures. Investigate the challenges posed by interacting networks, such as the Internet and electric power grid, and learn how these interactions can lead to cascading failures and novel phase transitions. Gain an understanding of how random graphs can model the consequences of interdependence between distinct networked systems. Cover topics including degrees of networks, random walks, large-scale connectivity, growth by overtaking, giant components, explosive percolation, dynamics on interdependent networks, and sociotechnical congruence.