This detailed and rigorous work gives empirical precision to the debate between ‘cyber-optimists’ who view the Internet as a ‘liberation technology’ (the flow of information and ideas becomes freer and facilitates events like the Arab Spring) and ‘cyber-pessimists’ who see the Internet as a ‘repression technology’ (such as for authoritarian governments which can use it as a means to increase surveillance and spread propaganda). Refreshingly, the authors find neither view satisfactory, as the Internet’s political impact is inherently multifaceted. One key finding of the book is that increased Internet penetration reduces the occurrence of protests. However, once a protest does start, the Internet helps to sustain it. Moreover, the Internet makes the spread of such protests to other places more likely. The Internet, then, is not the spark that starts the fire, but it does provide fuel when grievances have started fires by themselves. The book is partly a function of the creation of the Mass Mobilization in Autocracies Database (MMAD). The book and the database are dramatic improvements over earlier empirical works on protests in three important regards. The first two are inter-related: time and space. Most work on protests looks at single protest episodes in one country. At the time of writing, the MMAD captures 34,815 media reports, describing 19,329 protest events across 76 countries, spanning 13 years. As a data gathering project, this is hugely impressive. The third way in which the book and database score over earlier works is in the disaggregation: the database and the analysis in the book are based on carefully geo-coded data. Weidmann & Rød should be congratulated for producing such a well-crafted book.