TEFL is the work of teaching English to people whose first language is not English. It is an abbreviation: Teaching English as a Foreign Language. You say the letters one at a time, T-E-F-L, though a few people say it as one word, 'teffle'. The word points at a whole field, not at one lesson. When someone says 'I work in TEFL', they mean this is their job and their profession — teaching English abroad, or teaching foreign students, writing course books, training other teachers. You also see it in front of other nouns: a TEFL course, a TEFL certificate, a TEFL job, a TEFL teacher. Most often, though, people say TEFL when they mean the qualification. 'I'm doing a TEFL' means I am taking a short training course, usually a few weeks, that lets me go and teach English somewhere. That is how young people from Britain, Ireland, Australia and so on often start: finish university, do a TEFL, fly to Taiwan or Vietnam or Spain. The 'foreign' part carries a real meaning, though it has become slightly old-fashioned. Strictly, TEFL is teaching English in a country where English is not the daily language around you — so teaching English in Taipei is TEFL. Teaching English to immigrants living in London, where English is all around them, is called ESL or TESOL instead. Teachers themselves argue about these labels, and many now prefer TESOL because 'foreign' can sound as if the language belongs to some people and not to others. In ordinary talk, most people ignore the fine line and use TEFL for all of it. It is a work word. Your teacher may well have a TEFL certificate; you would not use the word about yourself as a student.

英語教學（以英語為外語的教學）；也常指「英語教學師資證照／課程」。在台灣，補習班和師資班多半直接講英文縮寫 TEFL，或說「TEFL 證照」，不太會說中文全名。注意它講的是「教」這件事，不是「學英文」。