If you are planning to teach English to non-native speakers, you will need to know the difference between a teaching English as a second language certification, usually referred to as TESL, and the Test of English as a Foreign Language, known as the TOEFL. The TOEFL is an internationally recognized standardized test for English as a second language students who are applying to universities and colleges in the United States. TESL represents a teaching certification for people who wish to teach English to non-native speakers of English.
Teaching English as a Second or Other Language -- TESOL
In the United States, TESOL refers to teaching English in an English-speaking country to students who are non-native speakers. TESL is a term used more widely in Canada and refers to the same certification. The requirements to become a TESOL instructor differ from state to state and also depend on the teaching situation. If you want to teach English as a second language to K-12 students, higher education students or overseas students, the requirements will vary.
Test of English as a Foreign Language -- TOEFL
This is not a teaching certification at all but refers to the Test of English as a Foreign Language, an international standardized test for students who are non-native speakers of English. If you want to enter a Canadian or an American university and English is not your native language, you will have to write the TOEFL. University program requirements may vary, but most enforce minimum scores for the reading, writing, listening and speaking portions of the exam as well as a minimum total score, usually 90 out of 120 points to successfully apply.
Teaching ESL in the United States
To teach K-12 ESL in the United States, you will need an undergraduate degree in education plus an ESL endorsement. The endorsement requirements vary by state and by school district. To teach ESL at a higher education institution, such as a college or university, you need: your master's degree in TESOL; a master of arts in a related field plus a TESOL certificate; or a master of education plus a TESOL certification. These requirements will vary from state to state and even from institution to institution but not significantly.
Teaching ESL Overseas
Every country has different requirements for ESL teachers. Some, like South Korea, require a bachelor's degree and TESOL certification but very little experience. Others, like the United Arab Emirates require certified teachers and a minimum of two years teaching experience. Several reputable online teacher-recruiting agencies can help match teachers' credentials and teaching experience to countries all over the world.