English as a second or foreign language is the use of English by speakers with different native languages. Instruction for English-language learners may be known as English as a second language (ESL), English as a foreign language (EFL), English as an additional language (EAL), or English for speakers of other languages (ESOL).

English as a second language (ESL) is often used for non-native English speakers learning English in a country where English is commonly spoken. English as a foreign language (EFL) is used for non-native English speakers learning English in a country where English is not commonly spoken. The term ESL has been misinterpreted by some to indicate that English would be of secondary importance. However, it simply refers to the order in which the language was learned, consistent with the linguistic terminology of second-language acquisition. The term ESL can be a misnomer for some students who have learned several languages before learning English. The terms English Language Learners (ELL), and more recently English Learners (EL), have been used instead, and the students’ home language and cultures are considered important.