Language and culture are closely entwined in the evolutionary development and contemporary diversity of human societies. Human language differs from animal communication in its complexity and flexibility, aspects of human communication made possible by unique human biological and genetic features. The complexity of language makes it a powerful tool in shaping human thought, providing categories and metaphors for organizing our information about the world. Though language shapes thought and action in universal ways, many aspects of language vary widely relative to local cultures. The social aspects of language are particularly relative, influencing how children learn languages in various sociocultural contexts as well as how people use language to create speech communities. In ritual contexts, language is used performatively to accomplish social action as well as challenging those actions. As a tool of power, language structures gender, race, and ethnic dynamics. Recognizing the fundamental importance of language to the preservation of culture, many Indigenous communities have developed strategies to revive their heritage languages using immersion schools and master-apprentice programs.