An ELT Glossary : ESL

ESL : English as a Second Language

Definition : The term ESL is generally used in British contexts to refer to a situation where a learner is learning English in an English speaking country, in order to live there and integrate into the culture. The learners may use their first language at home, but need English in the community, eg in shops and government offices, and at school or at work. The term ESOL 

Examples

• Learners at  school or university in their own country for whom English is an obligatory or chosen academic subject
• Learners in their own country attending a course at a private language school.

NB : In American contexts, the terms ESL and ESOL are often used to refer to learners learning the language in their own country - which in a British context would be called EFL.