TEFL, TESOL, and CELTA courses provide qualifications and training for teachers interested in teaching English abroad. Most of these courses last anywhere from a few days to about a month. If you're thinking of teaching English abroad then you may find a TEFL, TESOL, or CELTA course to be useful.

In much of Asia they are not technically required for a visa.

What's the worst course? Not sure, but online TEFL courses are considered by some to be the least reputable. Why? Because some employers prefer in-class training. However, many will not note the distinction between in-class courses and online courses. And they can't be all that bad if CELTA offers an online course. Online courses are often more convenient as you can take them from anywhere in the world and at your own pace.

What's the best course? Well as far as English language teaching certificates go typically CELTA is considered best. Trinity TESOL is also said to be reputable. CELTA is the most widely recognized and respected program.

However, it is not for everyone or every situation. It focuses on teaching adults. It's known as being expensive, intensive and if you don't pass you won't get a certificate. Some say that if you are only planning on teaching abroad for a year or so then it's probably not worth it and that you should only take a CELTA if you are in it for the long term. Read more about CELTA.

ESLinsider also offers a one of a kind online TEFL course.

Yes, teach me how to teach English abroad