Culture is the shared beliefs, behaviors, and practices of a social group. It includes both material and nonmaterial aspects. Material culture consists of objects like bus passes and churches, while nonmaterial culture includes ideas, attitudes, and beliefs. A society's culture is expressed through its values, beliefs, norms, symbols, and language. Cultural change occurs over time through innovation and cultural diffusion as new ideas and technologies spread. Sociologists view culture through different theoretical lenses such as functionalism, conflict theory, and symbolic interactionism.