This document discusses the main stages of English for Specific Purposes (ESP) development, including: 1) Classical/Traditional grammar, which had indirect influence but provided knowledge of how language operates. 2) Structural linguistics, which challenged classical descriptions in the 1930s and focused on syntagmatic structures and notions. 3) Transformational Generative grammar, which viewed language as more than a reflection of thought. 4) Functional/Notional grammar focuses on language use rather than basic grammar and considers structure, context, and function. 5) Language variation and register analysis consider language differences by context but cannot solely determine syllabus. 6) Discourse analysis examines how meaning is generated between sentences