Commodore was an early title and later a rank in the United States Navy, United States Coast Guard and the Confederate States Navy. For over two centuries, the designation has been given varying levels of authority and formality. Today, it is no longer a rank, but it continues to be used as an honorary title within the U.S. Navy and the U.S. Coast Guard for those senior captains (pay grade O-6) in command of operational organizations composed of multiple independent subordinate naval units (e.g., multiple independent ships or aviation squadrons).