In their pursuit of social justice, revolutionaries have taken on the assembled might of monarchies, empires, and dictatorships. They have often, though not always, sparked cataclysmic violence, and have at times won miraculous victories, though at other times suffered devastating defeat. This Very Short Introduction illuminates the revolutionaries, their strategies, their successes and failures, and the ways in which revolutions continue to dominate world events and the popular imagination. Starting with the city-states of ancient Greece and Rome, Jack Goldstone traces the development of revolutions through the Renaissance and Reformation, the Enlightenment and liberal constitutional revolutions such as in America, and their opposite--the communist revolutions of the 20th century. He shows how revolutions overturned dictators in Nicaragua and Iran and brought the collapse of communism in the Soviet Union and Eastern Europe, and examines the new wave of non-violent "color" revolutions--the Philippines' Yellow Revolution, Ukraine's Orange Revolution--and the Arab Uprisings of 2011-12 that rocked the Middle East. In this new edition, Goldstone also sheds light on the major theories of revolution, exploring the causes of revolutionary waves, the role of revolutionary leaders, the strategies and processes of revolutionary change, and the intersection between revolutions and shifting patterns of global power. Further, he explores the role social media and nonviolence play in modern revolutions. Finally, he examines the reasons for diverse revolutionary outcomes, from democracy to civil war and authoritarian rule, and the likely future of revolution in years to come.