The United States Navy (USN) is the naval warfare service branch of the United States armed forces and one of the seven uniformed services of the United States. In August 2010, the U.S. Navy had 330,729 personnel on active duty and 102,923 in the Navy Reserve. It operates 289 ships in active service and more than 3,700 aircraft. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S. Navy also has the world's largest carrier fleet, with 11 in service and one under construction.