Digital in the broad sense (computing, networks, media, internet) has invaded all human activities, from the most personal to the most collective, and has profoundly changed our relationship to others, space, time. This reference book presents the theoretical background and key concepts and a critical summary of the work carried out on the subject in the social sciences. This new edition takes stock of recent developments (the Machine Learning, blockchain, GDPR) and contemporary challenges (calls for regulation, China’s growing role, inflation of news fakes). It provides an overview of the latest developments in research: sociology of algorithms, propagations and makers; attention economics, parliamentarisation, trace and digital labor behavioural economics; digital policy analysis in justice, security, military or health; or new methods of ‘digital humanities’.