Simply stated, ESL is short for English as a Second Language. It isn’t too accurate a term, really, because English could be someone’s third or forth language or one hundredth. It is, however, a commonly used term that most learners of English and teachers recognize. Akin to that is EFL, English as a Foreign Language. From a teacher’s perspective, it’s almost the same thing. The only difference being that ESL is usually termed so if English is being taught in a native English speaking country (such as Canada, USA, Austrailia, Britain), and EFL if a teacher goes abroad from one of those countries and teaches English to those in Japan, for example, in a country that does not have English as its first language. From a Linguistics perspective, some may argue that teaching in an English-speaking country, “at home”, requires a different teaching approach than teaching in a classroom abroad. I almost said foreign classroom, but didn’t, and I didn’t because to state that word might infer that any place that is not thought of as native English speaking country would be deemed foreign, so any place outside of them, but that would be incorrect. It’s just perspective. The world is too multicultural now to have such a narrow view. ESL, EFL…it’s all English.