The Rules of Contagion: Why Things Spread and Why They Stop is a book written by Adam Kucharski, an epidemiologist at the London School of Hygiene and Tropical Medicine. Much of his work involves developing new mathematical and statistical approaches to understand the dynamics of infectious disease outbreaks. And Rules of Contagion goes beyond what we usually have in mind when thinking of infectious diseases or even viral online content. Kucharski examines other, less obvious outbreaks such as financial crises and epidemics of knife violence as well as obesity, smoking, and even loneliness. Using examples of biological and social processes he describes epidemics mathematically, explaining how Ebola, SARS or HIV spread and what we could learn from them. Reading it in times of global pandemic was undoubtedly a powerful experience and I would recommend it to anyone who would like to understand the Covid 19 crisis a bit better.