This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book is concerned with the use of discrete characteristics in the construction of both hate crime definitions and existing policy around the world. It offers a transnational snapshot of hate crime laws and some of the key debates and dilemmas that surround them. The book examines a range of issues relating to hate crime across Europe, and considers the efforts of international bodies to recognise, measure, and addresses the problem in different countries across the continent. It provides a useful historical account of the emergence and evolution of political concerns relating to hate and hate crime in Europe. The book analyses the factors informing and sustaining sectarian hostility, victimisation and segregation, with a view to understanding the changing nature of this deeply embedded form of prejudice.