What is the ASVAB
The Armed Services Vocational Aptitude Battery is an assessment  that measures your strong points as well as  weaknesses, that can predict your success in on of the Branches of the US Military. 

Your ASVAB Score can be critical
ASVAB test scores are divided into individual tests and the composite score of these specific subject tests. One of the most critical of these scores is the Armed Forces Qualification Test, which is used to determine if you are qualified to join the military service. Each service determines the qualification AFQT score for enlisting in their service.

The AFQT is your test results in Arithmetic Reasoning, Math Knowledge and Verbal Composite times two. The Verbal Composite score is the sum of your Word Knowledge and Paragraph Comprehension test scores. 

In addition, your scores on the other ASVAB composite tests will determine your career field or military occupation eligibility. Since enlistment bonuses are usually tied to your choice of occupations, the better the score, the more opportunities you have. But keep in mind, it is impossible to score perfect on the ASVAB, your goal should be to simply do the best you can.

There are nine section to the ASVAB

• General Science (GS)
• Arithmetic Reasoning (AR)
• Word Knowledge (WK)
• Paragraph Comprehension (PC)
• Mathematics Knowledge (MK)
• Electronics Information (EI)
• Auto Shop (AS)
• Mechanical Comprehension (MC)
• Assembling Objects (AO)

Each of the five armed services has its own aptitude area scores and sets its own minimum qualifying composite scores for each of its occupational specialties or ratings.  Service Branch  Required AFQT Score (is subject to change)  

• Army  31
• Navy  35  
• Marines  31 
• Air Force  36 
• Coast Guard  45