Walt Rostow was an American economist and political theorist, best known for his work on economic development and modernization. He served as an advisor to several U.S. presidents, including Lyndon B. Johnson, during the 1960s. Rostow is particularly famous for his book, "The Stages of Economic Growth," where he outlined a model of development that describes how countries progress through five stages. Rostow's theories emphasized the importance of industrialization and investment in infrastructure for economic growth. His ideas influenced U.S. foreign policy, especially in relation to Vietnam and other developing nations, as they sought to promote economic development as a means to achieve political stability.