CELTA caters for a wide range of people. CELTA is for those without previous experience who wish to become teachers of English to speakers of other languages and for teachers with no previous training in this field.
It is also for university graduates, people wanting to change job and try something else, travellers to Europe wanting to combine getting a teaching qualification while living in a European country.
If English isn't your first language, you can apply for the course as long as you "have an awareness of the language and a competence in both written and spoken English which will enable you to undertake the course and prepare for teaching a range of levels" (Cambridge guidelines).
Success in the Certificate has enabled many candidates to obtain their first English teaching position: the CELTA course is highly regarded by employers around the world as providing sound initial training and a strong basis from which to develop as a teacher of English.