The ensign is a maritime flag that is used for the national identification of a ship. The ensign is the largest flag, generally flown at the stern (rear) of the ship while in port. In ports, depending on the ship's origin, it is sometimes identical with a jack on the bow of the ship. Jacks are more common on warships than on merchant ships.
The Middle English ensign is derived from the Latin word insignia.
In vexillology an ensign is differentiated between a naval ensign (war ensign) and civil ensign (merchant), which both are the original expressions of the national flag.
However, in the United Kingdom, Germany and Netherlands a separation between State and Armed ships on the one hand, and unarmed and private vessels was made earlier than in other Nations, see British ensign.
Vexillologists distinguish three varieties of a national flag when used as an ensign:
Today, some countries like the United States and France still use just one flag and also as a jack, while lacking special cantons and transparent identification. All ships of the seagoing services of the United States Government with the exception of the United States Coast Guard fly the national flag as their ensign, although the ships of some agencies also fly an agency flag as a 'distinctive mark'.
However, further countries like Ukraine, Italy, Russia, South Africa, Australia, New Zealand and Japan use different ensigns. Such are strictly regulated and indicate if the vessel is a warship, a merchant ship, a ship under contract to carry mail, or a yacht, for example.
Several Commonwealth countries' national flags had their origin in the ensigns of their original colonising power, the United Kingdom. Most notable of these national flags are those of Australia, New Zealand, and several smaller island nations. It is also very likely that the Grand Union Flag from which the flag of the United States developed was strongly influenced by the British Red Ensign or the flag of the (British controlled) East India Company.
In nautical use, any boat uses a specific flag of a specific Nation to indicate its organizational membership. The ensign is flown on a ship for that reason. The flag signifies the home port of the ship owner and that his tax is paid there for his income made with the ship. Flagging out always means that the relevant laws of the country apply on the ship like employment contracts, safety, stamp duty or value-added taxes.
In most countries, especially in Europe and the countries of the Commonwealth of Nations, it is common for the ensign to display additional information as well. For example, whether it is a civil, state or military flag.
Ensigns are usually at the stern flagstaff when in port, and may be shifted to a gaff (if available) or mast amidships when the ship is under way, becoming known as a steaming ensign.
A boat flag is also often used as guest country flag and is flown on the boat when navigating in foreign waters or entering another country's port.
With the creation of independent air forces and the growth in civil aviation in the first half of the 20th century, a range of distinguishing flags and ensigns were adopted. These may be divided into air force ensigns (often light blue in colour, such as the Royal Air Force Ensign) and civil air ensigns.
In heraldry, an ensign is the ornament or sign, such as the crown, coronet, or mitre, borne above the charge or arms.
The Blue Ensign as currently used for British government vessels
The Red Ensign as currently used for British civilian vessels
The Civil Air Ensign as currently used by UK civil aviation establishments
Australian national Flag and State Ensign
New Zealand Red Ensign
Indian Navy Ensign
Civil and Naval ensign of Albania
Belgian Navy Ensign
Ensign of the Royal Danish Navy
Egyptian Navy Ensign
Civil and Naval Ensign of France
Naval ensign of Italy
Luxembourg Civil Ensign
Myanmar Navy Ensign
Royal Netherlands Navy Reserve ensign
Nigerian Navy ensign
North Korean Navy Ensign
Ensign of the Royal Norwegian Navy
Polish Navy Ensign
Naval Ensign of the Royal Saudi Navy
Spanish yacht ensign
Naval ensign of Sri Lanka
Naval ensign of Royal Thai Navy
Ukrainian Navy Ensign
United States Coast Guard ensign
Naval ensign of Vietnam