The Test of English as a Foreign Language (TOEFL) is the best test to take if you want to study in the US or Canada. It is recognized as the standard test of English ability by most North American universities and graduate schools. The TOEFL is now so popular that it is also accepted in institutions around the world and for migration purposes in countries like Australia.
Over the years, the test has gone through a number of big changes. Today it is known as the TOEFL iBT (internet-based test), and the test taker interacts online for all four of the language skills. This can be a bit strange at first, but with some practice it gets much easier.
There are test centres all over the world. Be aware that some places are very popular, which can make it tricky to get a last-minute booking. Make sure you book ahead! Another positive thing about the TOEFL is that you get the results back very quickly.
To get a score that properly reflects your ability, make sure you get really familiar with how the TOEFL iBT works before taking it. The highest score is 120, with a mark out of 30 for each skill. Universities usually require a score of 80 or higher for the iBT, but requirements do vary from institution to institution. Make sure to check the prerequisites with the university you want to go to before booking your test.