Deviance refers to behaviour that violates the standards of conduct or expectations of a group or society. What is considered deviant varies across cultures, social groups, and time periods, as it is defined by social norms and values. Deviant behaviour can range from minor infractions of social norms to serious violations of laws. Sociologists study deviance to understand why people violate norms, how societies react to deviance, and the role of deviance in social change. Various theories attempt to explain deviance, including anomie theory, differential association theory, control theory, and labeling theory. Deviance is not inherently negative; while some deviant acts are harmful, others can challenge existing norms and lead to social progress.