an organization of ships, aircraft, Marine forces, and shore-based activities all under the command of a commander or a commander-in-chief who may exercise operational as well as administrative control
Administratively, several ships of the same type (e.g., destroyers) are organized into a squadron. Several squadrons in turn form a flotilla, several of which in turn form a fleet. For operations, however, many navies organize their vessels into task units (3–5 ships), task or battle groups (4–10 ships), task forces (2–5 task groups), and fleets (several task forces).