A command in military terminology is an organisational unit for which a military commander is responsible. Commands, sometimes called units or formations, form the building blocks of a military. A commander is normally specifically appointed to the role in order to provide a legal framework for the authority bestowed. Naval and military officers have legal authority by virtue of their officer's commission, but the specific responsibilities and privileges of command are derived from the publication of appointment.

The relevant definition of "command" according to the United States Department of Defense is as follows:^[1]

(DOD) 3. A unit or units, an organization, or an area under the command of one individual. Also called CMD. See also area command; combatant command; combatant command (command authority).

Major Command or Major Commands are large formations of the United States Armed Forces. Historically, a Major Command is the highest level of command. Within the United States Army, the acronym MACOM is used for Major Command.^[2] Within the United States Air Force, the acronym MAJCOM is used.^[3][4]

There are several types of Major Commands in the United States Armed Forces:

• List of major commands of the United States Air Force
• List of major commands of the United States Army
• Naval Education and Training Command of the United States Navy

• Arctic Command
• Chain of command
• Command and control
• Major Command
• Military organization
• Tactical formation
• Unit cohesion