This document provides definitions and discussions of key concepts in linguistics from several experts and scholars. It discusses language as a systematic, symbolic, arbitrary, primarily vocal, and human-specific method of communication. Key features of language highlighted include that it is systematic, symbolic, arbitrary, vocal, human-specific, and used for communication. The document also covers the origin of language, language families, the field of linguistics, and important linguistic concepts such as langue and parole, prescriptive vs descriptive, synchronic vs diachronic, syntagmatic vs paradigmatic, competence vs performance, and form vs function.