Book excerpt: During the Covid-19 pandemic, the term "vulnerable" was applied to "individuals" and to "populations", "groups" and "countries" in discussions, laws and regulations; now it applies to all objects in relation to all kinds of threats. However, rather than a label for governing people and places, the notion of "vulnerability" was expected to become an instrument to tackle the root causes of disasters, poverty and maldevelopment, as well as the inequalities and injustices they bring, whether social, political, economic or environmental. Despite this radical dimension, vulnerability has gradually been incorporated into public policies and international recommendations for global risk and disaster management. This book is intended for researchers, students, managers and decision makers concerned with the management of not only risks and crises but also climate and environmental change. The first part examines the multiple theoretical and conceptual approaches; the second explores vulnerability assessments, using examples from the Global North and Global South; and the third discusses tools, public policies and actions taken to reduce vulnerability.