There are thousands of ESL teaching courses available, with all sorts of claims being made about them and accreditation that can be valid or bogus. One simple test is to look at adverts to see what employers are looking for, so I went through 200 adverts for basic teaching jobs around the world, and a few teaching online. I ignored managerial positions, university and specialist jobs. This does not rate the contents of courses, though it is clear which courses employers trust and prefer. Qualifications are given with the percentage of the teaching jobs advertised that a person could apply for.