Sociology is the study of society. It is a social science—a term with which it is sometimes synonymous—which uses various methods of empirical investigation and critical analysis to develop and refine a body of knowledge about human social activity, often with the goal of applying such knowledge to the pursuit of social welfare. Subject matter ranges from the micro level of agency and interaction to the macro level of systems and social structures.
Sociology is both topically and methodologically a very broad discipline. Its traditional focuses have included social stratification, social class, social mobility, religion, secularisation, law, and deviance. As all spheres of human activity are sculpted by social structure and individual agency, sociology has gradually expanded its focus to further subjects, such as health, military and penal institutions, the Internet, and even the role of social activity in the development of scientific knowledge.