Sociology is the systematic study of human society and social interaction. It examines how social institutions influence human behavior and the processes that maintain and change society. The field was established in the 19th century by thinkers seeking to apply scientific methods to the study of human relationships. Sociology takes three main theoretical perspectives: structural functionalism, which focuses on social stability and the interdependence of institutions; social conflict theory, which examines power struggles and inequality; and symbolic interactionism, which analyzes how social structures emerge from everyday interactions and use of shared symbols. Sociology studies the rules that govern human social life and how social environments shape psychological behaviors. It examines topics like community development, social change, and the relationships between society's institutions.