This document discusses the foundations of language teaching from sociolinguistic and psycholinguistic perspectives. It addresses what a language teacher needs to understand, including the nature of language and how people learn and teach languages. Language is defined as a systematic set of symbols used for communication within a culture. Learning involves acquisition, retention through memory, and a change in behavior. Teaching guides and facilitates learning by setting conditions for it. Theories of language and learning have evolved from behaviorist to cognitive to generative frameworks.