The document provides an overview of various linguistic theories and their implications for English for Specific Purposes (ESP), including: 1. Traditional grammar focuses on the role of words in sentences, while structural linguistics describes grammar through sentence structures. 2. Transformational generative grammar examines deep and surface language structures and meanings. 3. Functional and notional approaches consider language functions and notions for establishing language equivalencies across syllabuses. 4. Discourse analysis looks at language use beyond the sentence through dialogues, rhetorical techniques, and text diagrams.