ESL refers to English language learning in countries where English is the main and / or official language, and the student's own native language (first language) is not English. This term is problematic when we consider learners for whom English is their third or fourth language.
English as a Second Language (ESL or TESL) is a traditional term for the use or study of the English language by non-native speakers in an English-speaking environment. That environment may be a country in which English is the mother tongue (e.g., Australia, the U.S.) or one in which English has an established role (e.g., India, Nigeria). Also known as English for speakers of other languages.