What type of flag is used on aircraft, ships, and boats?

The flag used on aircraft, ships, and boats is referred to as an ensign. This designation is significant because the ensign represents the nationality of the vessel or aircraft and is often flown at the stern of a ship or on the tail of an aircraft to identify its country during operations and in international waters. The ensign serves as a symbol of sovereignty and is an essential part of naval protocol.

In contrast, guidons are flags used by units in the Army and are typically smaller, serving to represent a particular company or battalion. Pennants are flags, often triangular, used for signaling or decorative purposes rather than to denote nationality. Standards are similar to flags but are often used in ceremonial contexts and may represent specific regiments or units rather than vehicles like ships and aircraft.