John Bates Clark was an influential American economist born on January 24, 1847, in Providence, Rhode Island. He is best known for his contributions to the field of microeconomics and for developing the concept of marginal utility, which explains how consumers make choices based on the additional satisfaction gained from consuming one more unit of a good or service. His work laid the foundation for modern economic theory. Clark was also a prominent advocate for the idea of welfare economics, which examines how economic policies can improve social welfare. He served as a professor at several universities, including Columbia University, and was a founding member of the American Economic Association. His ideas continue to influence economic thought today.