Arthur Okun was an American economist best known for his work on the relationship between unemployment and economic output. He served as the chairman of the Council of Economic Advisers under President Lyndon B. Johnson and contributed significantly to economic policy during the 1960s. His most famous concept, Okun's Law, describes how a decrease in unemployment leads to an increase in a country's gross domestic product (GDP). In addition to his policy work, Okun was a professor at Yale University and authored several influential books and articles on economics. His research helped shape modern economic thought, particularly in understanding the dynamics of labor markets and economic growth. Okun's legacy continues to influence economists and policymakers today.