Robert D. Putnam is an American political scientist and professor known for his work on social capital and civic engagement. He gained prominence with his book, Bowling Alone: The Collapse and Revival of American Community, published in 2000, which discusses the decline of social connections in the United States and its implications for democracy and society. Putnam's research often explores the relationship between community involvement and various social outcomes. He has also studied the impact of education, economic inequality, and political participation on social cohesion, contributing significantly to the fields of political science and sociology.