This process can be time consuming and stressful, but if you are not happy with your score you can always take the test again.
As a general rule, if you are a foreigner you will have to take the TOEFL (Test of English as a Foreign Language) to be able to study in the U.S. The TOEFL is a standardized test required for non-native English-speaking students. There are two versions of the test - a written one and a computer-based one. If you need to take the test visit www.ets.org, the official website of TOEFL.
The Graduate Management Admission Test (GMAT) is a four-hour test measuring verbal, quantitative and analytical ability and is often required by business schools. This computer-based test is an adaptive one, which matches its questions to your skill level. The test begins with questions of average difficulty. If you get the first one right, it will give you a harder one. If you are planning to do an MBA in the States, you need to take this test. Note that the GMAT is the same both for American and foreign students, so you will need sufficient language skills to pass it.
The SAT is required for admission to undergraduate programs by most American universities. The test is divided into two parts and the university can require you to take one or both tests. The SAT is a general test of verbal and quantitative reasoning.
SAT-I Reasoning Test: The SAT-I is a three hour, mainly multiple-choice test that measures verbal and mathematical reasoning abilities that develop over time. Most colleges require SAT-I scores for admission.
SAT-II Subject Tests: The SAT-II subject tests are one hour, primarily multiple-choice tests that measure your knowledge of particular subjects and your ability to apply that knowledge. Many universities may require you to take this along with SAT-I.
The GRE (General Record Examination) is a test required by many American graduate schools. The GRE general test measures verbal, quantitative, and analytical abilities. There are also different subject tests which cover different academic areas in depth. The writing assessment is a two-part test that evaluates writing and critical thinking skills. This computer-based test is an adaptive one; it matches its questions to your skill level and, as a general rule, the early questions are heavily weighted. Take your time at the beginning to get a better score.