David North's activity in the international workers and Trotskyist movement, as a revolutionary journalist, historian and political leader, spans more than half a century. He is presently the chairman of the Socialist Equality Party in the United States, and has served as the chairman of the International Editorial Board of the World Socialist Web Site (wsws.org) since its founding in 1998. North has written extensively on Marxist theory, the history of socialism and the Fourth International, the geopolitics of US imperialism, and the strategy and program of the present-day struggle for socialism. His books include The Heritage We Defend; In Defense of Leon Trotsky; The Russian Revolution and the Unfinished Twentieth Century; A Quarter-Century of War: The U.S. Drive for Global Hegemony 1990-2016; and Leon Trotsky and the Struggle for Socialism in the Twenty-First Century.