Subject Tests usually referred to as SAT II is an hour-long, content-based tests that allow you to showcase achievement in specific subject areas where you excel. These are the only international admission tests where you choose the tests that best showcase your achievements and interests as a prospective undergraduate.
SAT Subject Tests allow you to differentiate yourself in the University admission process or send a strong message regarding your readiness to study specific majors or programs in University. In conjunction with your other admission credentials (your high school record, SAT exam scores, teacher recommendations, etc.), they provide a more complete picture of your academic background and interests.
Some universities also use Subject Tests to place students into the appropriate courses. Based on your performance on the test(s), you could potentially fulfill basic requirements or receive credit for introductory-level courses.