This document provides definitions and explanations of English for Specific Purposes (ESP). It discusses how ESP has evolved over time, narrowing and widening in perspective. The main definitions from the last three decades are then reviewed. Hutchinson and Waters (1987) define ESP as an approach rather than a product, not restricted to specialized varieties of English and not related to any particular methodology or materials. Courses should be based on underlying competence rather than surface features of language. Vocabulary and examples of asking and giving information about physical appearance and personality are provided to describe people in English.