This document provides an introduction to sociolinguistics. It begins by defining sociolinguistics as the study of how social factors influence language use and how language varies based on social contexts. It then discusses linguistic variation in terms of variables and variants. Finally, it explores the differences between language, variety, dialect, and code, noting that the distinction between them is not always clear cut. Sociolinguists generally use the term "variety" to refer to any set of linguistic forms that pattern according to social factors.