An aptitude test is designed to measure a person's ability to acquire some specific set of skills. These tests are based on the assumption that different people have different levels of aptitude and that these levels are measurable.
An aptitude test, which is an attempt to measure future ability, is distinguished from an achievement test, which is designed to measure already-acquired skills or knowledge. Sometimes the two types of tests are combined, as in the Scholastic Aptitude Test, or SAT, which is designed as an aptitude test but also measures achieved knowledge. Aptitude tests can measure both the ability to reason quickly and fluidly and the ability to learn from past experiences.