TESL stands for 'Teaching English as a Second Language', and usually refers to teaching English to non-native speakers in a country where English is actually the native language, such as Britain or the USA.
TESOL means 'Teaching English to Speakers of Other Languages' and is basically the same thing as TEFL and TESL to all intents and purposes. It is more common in the USA than TEFL but there isn't really much difference.
ELT means English Language Teaching
EMT means 'English Mother Tongue', and is often seen in adverts for English teachers meaning that they prefer native speakers.
CELTA stands for 'Certificate in English Language Teaching to Adults, and is synonymous with the Cambridge TEFL Certificate, which the TEFL Paris Certificate follows closely.
DELTA stands for (did you guess?) 'Diploma in English Language Teaching to Adults' and is where you go when you have a few years' experience and want to take your knowledge and skills to the next level!
EAP is 'English for Academic Purposes' and 'ESP' is 'English for Special Purposes'. ESP in particular is a growing field and covers specialised industry-specific materials such as nursing, IT, law or pilots and air traffic controllers.
IATQUO is our independent moderating body, and stands for 'the International Accreditation of TESOL Qualifying Organisations'. They are an extremely competent and rigorous organisation who insist on excellent internationally recognised standards from the schools who wish to use their name. To read a comprehensive document on choosing your TEFL Certificate Course, fully endorsed by IATQUO and many other reputable and independent accrediting bodies, click here.