An APO or FPO address is an abbreviation used by the US Military Postal Service to deliver mail and packages to military personnel overseas. APO stands for Army Post Office and is associated with the US Army and Air Force, while FPO stands for Fleet Post Office and is associated with the Navy and its ships. Military addresses must show the grade, full name with middle name or initial, and PSC number, unit number, or ship name. The city name should be replaced with "APO" or "FPO," and the state with "AA," "AE," or "AP," and a special ZIP Code should be used. All APO/FPO shipments must be made using the United States Post Office (USPS) .