Chapter 3 discusses the linguistics of second language acquisition (SLA), highlighting various approaches, such as contrastive analysis and error analysis, alongside Noam Chomsky's theories on universal grammar. It emphasizes the systematic, symbolic, and social nature of language, and the dynamic interlanguage that learners develop as they acquire a second language. Key concepts include the role of innate knowledge in language acquisition and how different factors, such as age and social context, influence the learning process.