Charles Horton Cooley was an American sociologist born in 1864. He is best known for his concept of the looking-glass self, which describes how individuals form their self-concept based on their perceptions of how others view them. Cooley's work emphasized the importance of social interactions in shaping identity and behavior. Cooley also contributed to the development of symbolic interactionism, a theoretical framework that focuses on the meanings individuals derive from social interactions. His influential writings, particularly in the early 20th century, laid the groundwork for modern sociology and helped to establish the significance of social relationships in understanding human behavior.