A commissioned officer is a military leader who holds their authority through an official document called a commission, usually signed by the president or head of state. This commission grants them the legal power to command troops and make important decisions in the armed forces.

Commissioned officers include ranks like lieutenant, captain, major, colonel, and general in the Army, Air Force, and Marines, or ensign, lieutenant, commander, and admiral in the Navy and Coast Guard. They're different from enlisted personnel (regular service members) and non-commissioned officers or NCOs (experienced enlisted members like sergeants who lead small groups).

To become a commissioned officer, someone typically graduates from a military academy like West Point or Annapolis, completes officer training school, or earns a commission through a college ROTC program. The training prepares them to lead others, make strategic decisions, and take responsibility for the troops under their command, in addition to developing their combat skills.