As an adjective, military originally referred only to soldiers and soldiering, but it soon broadened to apply to land forces in general, and anything to do with their profession.[2] The names of both the Royal Military Academy (1741) and United States Military Academy (1802) reflect this. However, at about the time of the Napoleonic Wars, 'military' began to be used in reference to armed forces as a whole,[2] and in the 21st century expressions like 'military service', 'military intelligence', and 'military history' encompass naval and air force aspects. As such, it now connotes any activity performed by armed force personnel.

As of 2017, the U.S. spends about US$610 billion annually to fund its military forces and Overseas Contingency Operations.[4] 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.[10] 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.[11] [12][13]

Each of the five services employs a single Senior Enlisted Advisor at departmental level. This individual is the highest ranking enlisted member within that respective service and functions as the chief advisor to the service secretary, service chief and Congress on matters concerning the enlisted force. These individuals carry responsibilities and protocol requirements equivalent to three-star general or flag officers. They are as follows:
Examinees also receive a score on what is called the Armed Forces Qualification Test (AFQT). AFQT scores are computed using the Standard Scores from four ASVAB subtests: Arithmetic Reasoning (AR), Mathematics Knowledge (MK), Paragraph Comprehension (PC), and Word Knowledge (WK). AFQT scores are reported as percentiles between 1-99. An AFQT percentile score indicates the percentage of examinees in a reference group that scored at or below that particular score. For current AFQT scores, the reference group is a sample of 18 to 23 year old youth who took the ASVAB as part of a national norming study conducted in 1997. Thus, an AFQT score of 90 indicates that the examinee scored as well as or better than 90% of the nationally-representative sample of 18 to 23 year old youth. An AFQT score of 50 indicates that the examinee scored as well as or better than 50% of the nationally-representative sample.