Official language exams: TOEFL

TOEFL exam refers to Test of English as a Foreing Language. It is similar to the exams of Cambridge: FIRST and ADVANCE in the way they work. They are formed by four different parts: writing, listening, speaking and reading. But the main difference you have to learn American English instead of British. It is quite similar but not exactly the same. TOEFL exam is around 4 hours and there are different models: traditional one or online.

Also, the price of the TOEFL is very expensive but, it depends the country and the university you decide to do it. Anyway it is around 150 Euros. I guess the worst part of TOEFL is the validity. It is an exam that expires in two years. As well you can use it in your CV, specially when you travel to Canada, USA or Australia.