This document provides an overview of applied linguistics, semantics, and lexis. It begins with definitions of language and linguistics, and outlines the main branches of linguistics including semantics. The scope and difficulties of studying meaning are discussed. Theories of semantics and key concepts in lexis such as word classes, collocations, and the lexical approach to language teaching are summarized. The document is presented as teaching materials on applied linguistics with a focus on semantics and lexis.