This paper discusses the importance of English for Specific Purposes (ESP) and traces its historical growth. It comprises the attempts of linguists to define it, each from a different prospective. This review also attempts to find out the purpose of ESP and its scope and how ESP courses are different from General English (GE) courses as well as the features and the requirements of an ESP course. It also discusses the needs analysis that is a crucial requirement for an ESP course and the importance of ESP courses for students as well as professionals. It discusses the teaching and learning process of an ESP course and highlights the fact that the creation, planning and structuring of an ESP course is a very challenging mission because it has to be tailored to the requirements of its learners.