A percentile measures the percentage of scores equal to or less than the scores of all other test takers. Percentile, like percentage, falls on a continuum from 0 to 100.

For instance, if someone takes an aptitude test for your company and scores in the 90th percentile, that means that 90% of all people who have taken the same test scored below that person. In other words, the person had a test score that is higher than 90% of the other test takers.