Cultures have worldviews, social institutions, and behavioral norms that tell us how to live and meet our needs. Often these ways of living are described in storytelling of various types. Cultures develop and change in response to physical, social, and cognitive environments. When people migrate, they can vary in how strongly they adhere to their old culture, and how strongly they adapt to the new culture. Governments exist at various levels to ensure that needs are met, especially ones that are not easily met by individuals. Ways of living and meeting needs are often specified in social, religious, and legal rules. Political differences can arise when people want to establish or eliminate social and religious rules as legal rules.