Anthropology is the study of human beings and cultures. It examines human cultural similarities and differences, as well as human biological diversity and evolution. Anthropology takes a holistic and relativistic approach to understand cultures from the perspective of cultural insiders. The four main subfields are socio-cultural anthropology, archaeological anthropology, linguistic anthropology, and biological/physical anthropology. Culture is learned, symbolic, shared, integrated, and dynamic. It includes both material and nonmaterial aspects such as values, beliefs, and norms. Cultures change through mechanisms like diffusion, acculturation, and invention.