What is the idea of ‘peace’? Is peace merely the absence of war, or can it also mean something else? Is peace a condition of emancipation, the status quo, or is it a system of hegemonic stability? How can peace be acquired whatever it may mean? And above all, what is the relationship between peace and war? This textbook aims to offer a comprehensive and up-to-date introduction to studies of peace and war, from both theoretical and empirical perspectives. Rather than providing students the answer of what the idea of peace means, this volume is designed to make and assist students to contemplate how peace can be thought by investigating its opposite: ‘war’, broadly defined.