If English is not your mother tongue or you are applying to a college or university from outside North America, you may be asked to demonstrate your proficiency in English.  A large number of schools will ask that you take either the TOEFL (“Test of English as  a Foreign Language”) or the IELTS (“International English Language Testing System). The TOEFL is a U.S. based test and will test American English. The IELTS is a British based test and will test British English.

Here is an article to help you decide wither to take take the TOEFL or IELTS.