First language acquisition is the fascinating process by which children learn their native tongue from birth to early childhood. It involves developing skills in various linguistic areas and follows a predictable sequence of stages, influenced by both innate biological factors and environmental input. Key theories in this field include behaviorist, nativist, interactionist, cognitive, and usage-based approaches. These theories offer different perspectives on how children acquire language, ranging from emphasizing environmental input to proposing innate linguistic knowledge and highlighting the role of social interaction.