The United States Navy has nearly 500,000 personnel, approximately a quarter of whom are in ready reserve. Of those on active duty, more than eighty percent are enlisted sailors, and around fifteen percent are commissioned officers; the rest are midshipmen of the United States Naval Academy and midshipmen of the Naval Reserve Officer Training Corps at over 180 universities around the country and officer candidates at the Navy's Officer Candidate School.

Sailors prove they have mastered skills and deserve responsibilities by completing Personnel Qualification Standards (PQS) tasks and examinations. Among the most important is the "warfare qualification", which denotes a journeyman level of capability in Surface Warfare, Aviation Warfare, Naval Aircrew, Special Warfare, Submarine Warfare or Expeditionary Warfare. Many qualifications are denoted on a sailor's uniform with U.S. Navy badges and insignia.