As of 2017, the U.S. spends about US$610 billion annually to fund its military forces and Overseas Contingency Operations. Put together, the U.S. constitutes roughly 40 percent of the world's military expenditures. The U.S. Armed Forces has significant capabilities in both defense and power projection due to its large budget, resulting in advanced and powerful technologies which enables a widespread deployment of the force around the world, including around 800 military bases outside the United States. The U.S. Air Force is the world's largest air force, the U.S. Navy is the world's largest navy by tonnage, and the U.S. Navy and the U.S. Marine Corps combined are the world's second largest air arm. In terms of size, the U.S. Coast Guard is the world's 12th largest naval force. 
Prospective service members are often recruited from high school or college, the target age ranges being 18–35 in the Army, 18–28 in the Marine Corps, 18–34 in the Navy, 18–39 in the Air Force and 18–27 (up to age 32 if qualified for attending guaranteed "A" school) in the Coast Guard. With the permission of a parent or guardian, applicants can enlist at age 17 and participate in the Delayed Entry Program (DEP), in which the applicant is given the opportunity to participate in locally sponsored military activities, which can range from sports to competitions led by recruiters or other military liaisons (each recruiting station's DEP varies).
It’s best to keep the contact information of your nearest recruiting office or your actual recruiter; they are your best bet for getting your scores. ASVAB scores are valid for up to two years before you need to retest so most offices will send your current scores via mail. If you can’t get yours by mail, you can pick them up from your local recruiting office.
A good score on the ASVAB is different than a minimum required score. Each of the military branches will have their own minimum required scores (see below). In practice, however, each branch will be more selective in their recruiting. A score of 50 on the ASVAB implies that you scored as well or better than 50% of comparable test-takers. Since ASVAB scores are used for many purposes (e.g., enlistment eligibility, military job placements, and career exploration), it is important that you score well on the ASVAB. A score of 60 or better should be your minimum target.
The Armed Forces Qualification Test (AFQT) is used by all of the Services to determine if an applicant is eligible for the military. Four of the ASVAB subtests are combined to form the AFQT. It measures general cognitive ability and is composed of verbal and mathematics subtests. AFQT scores are grouped into categories for reporting purposes. The table below shows the AFQT categories and the percentile score ranges corresponding to the categories. Applicants that score in AFQT category IIIA or higher may qualify for enlistment incentives.