ESP is an approach to teaching English, not a product. According to Hutchinson and Waters, ESP has specified objectives to teach English for specific purposes. There are two main types of ESP - English for Academic Purposes (EAP) and English for Occupational Purposes (EOP). EAP includes English for subjects like medicine, while EOP includes English for jobs like technicians. ESP courses can be further defined based on learners' fields, including English for Science and Technology (EST), English for Business and Economics (EBE), and English for Social Sciences (ESS). The key aspect of ESP is that it is an approach tailored to learner needs, not a distinct variety or type of English.