The TOEFL (Test of English as a Foreign Language) is one of the most widely used English language proficiency tests in the world. The results of this test are recognized universally.
The TOEFL ITP has been developed especially for educational institutions. This is a shorter and less expensive version of the full TOEFL exam. Please note that this is an institution-specific test, meaning results are only valid at VU Amsterdam, and not at other institutions.
Also see the information on other English language proficiency tests.