Book excerpt: Experts have documented an explosive rise in the number of hate groups since the turn of the century, driven by anger over immigration and demographic projections showing that whites will no longer hold majority status in the United States by 2040. The rise accelerated with the elections of presidents Obama and Trump. Extremists are increasingly diffuse, moving to the web and away from organized, on-the-ground activities. What is a hate group and how does it operate? How do we legally define hate speech and hate crimes? What is the history of organizing around hate and how do we recognize and confront it? These are the salient issues readers will investigate in this overview.