The Acronyms for TEFL, TESOL, SLA, L.1, and L.2

TEFL is an acronym which stands for Teaching English as a Foreign Language. This applies where English is learned and taught in an environment where English is not the official or unofficial first language, such as in Egypt, Spain or Saudi Arabia. TESL. Teaching English as a Second Language. This applies to situations where English is learned and taught in an environment where English is used on a daily basis as either an official or unofficial second language, such as in India, Singapore and Canadian Immigrants. TESOL. Teaching English to Speakers of Other Languages. This term is used both for the TEFL and TESL situations where the mother tongue of learners is not English.

ESL. English as a Second Language .This term is now widely used in situations where English is taught to non native speakers in a native English speaking country, such as in the USA, Canada, South Africa or New Zealand. ELT. English Language Teaching. A general term for the teaching of English in any of the mentioned learning situations. ESP. English for Special Purposes. This term is used for the particular English required for special situations. Such as, English required in business situations, academic purposes or in the tourism industry. Some TESOL training courses contain ESP courses. EYL. English for Young Learners. CELTA. Certificate in English Language Teaching for Adults.

Some TESOL training courses also offer courses relating specifically to teaching English to Children of seventeen years or under. SLA. Second Language Acquisition. L.1 an ESL student's first language. L.2 the language an ESL student or language learner is studying.

Reference:

The Cambridge guide to Teaching English to Speakers of other Languages
Edited by Ronald Carter & David Nunan.