The Armed Services Vocational Aptitude Battery (ASVAB) consists of a series of tests that the US military uses to judge the suitability of potential recruits. This test battery is usually taken by students in high school, particularly in their junior and senior years. Anyone else that could otherwise enlist may take the battery as well. The battery consists of tests that ascertain knowledge, cognitive reasoning abilities, and stress reactions. Each branch of the US armed services uses a different metric based on the ASVAB to determine eligibility, and the tests may also be used to ascertain aptitude for civilian careers.
Since 1976, every branch of the United States military has used the ASVAB to judge suitability for enlistment. The components of the battery include tests in areas such as vocabulary, mathematics, reading comprehension, and technical knowledge. Scores from four of the tests in the battery make up the Armed Forces Qualification Test (AFQT), which each of the US military branches actually use to determine suitability.
Both the ASVAB and the AFQT use normalized scores so that the AFQT number indicates how well an individual did in relationship to others that take the test. Those that score below the 10th percentile are forbidden by law from enlisting, though aside from that each branch has its own minimum AFQT score. In practice, the actual numbers required range from about 30 to 65, depending on the branch and whether the enlistee has a high school diploma or a general education development (GED) degree. Enlistees with GEDs are typically held to a higher standard unless they have a completed a certain number of college level courses.
Aside from the AFQT score that determines eligibility for enlistment, the other tests in the ASVAB can be used to qualify an individual for a specific military occupation specialty (MOS). Each soldier, airman, or marine's MOS is essentially his job, which can include diverse positions such as clerical work, mechanical maintenance, and combat operations. For each branch of the military and MOS, there is a different requirement for a line, composite, or aptitude area score. These different scores refer to various configurations of test results from the ASVAB.
The various tests that make up the ASVAB can also be useful in determining aptitude for civilian careers. Most people that take the test battery are interested in a military career, though anyone that wants to take the test is typically allowed. The battery tests a wide range of theoretical and applied knowledge, so the results can be useful in choosing the best career to pursue.