This document discusses various theories of language acquisition from different perspectives including behaviorism, cognitivism, nativism, and social interactionism. It covers key concepts in linguistics, psycholinguistics, language comprehension and production, second language acquisition, and influential theorists such as Skinner, Piaget, Chomsky, and Vygotsky. The theories explore how language is acquired through rewards/punishments, cognitive development stages, innate universal grammar principles, environment, and social interactions within one's zone of proximal development.