At the undergraduate level of college admissions there is one main test that every future college student needs to take, the SAT. Many colleges also require a general entrance exam and perhaps even the ACT. The vast majority of colleges, however, will require SAT scores in the range of 1000 to 1400 within a possible range of 400 to 1600. A score in the range of 1400 to 1600 will allow you to choose to attend some of the top colleges in the world.
Graduate schools will use either the GRE (a general test similar to the SAT), LSAT (a test specific to law schools), MCAT (a test specific to medical schools) or the GMAT (a test specific to business schools). Each of these tests has its own grading scale and score system. Additionally, each test covers different material and should be attempted using different strategies.
The one thing that each of these tests has in common is the percentile ranking which accompanies any score. When you receive your scores you should quickly scan to find your percentile ranking in each section of the test as well as your overall rank. A score in the 90th percentile means that you did better than 90 percent of the students who took this test. This would place you in the top 10 percent and should open the door to your choice of college. Students who score in the 50th percentile can either study more and pull up their score or settle for one of the many other colleges which are not in the Ivy League.