Networks are everywhere. From the social connections we make on platforms like Facebook, to the technology behind the Internet upon which these sites run, they have become an integral part of our daily lives. In this course, we will study these networks. Specifically, we will focus on understanding the fundamental principles that guide their designs and sustainability. We will see how the simplest phrases like “sharing is hard” and “crowds are wise” can summarize a vast amount of network theory, that goes into answering questions like “how does 3G work on your smartphone?” and “when can you trust an average rating on Amazon?”. And rather than using heavy math, this course will only require basic arithmetic such as addition and multiplication. We rely on animations, analogies, and anecdotes as our pedagogical tools, in lieu of detailed equations.