Ensign

A maritime flag showing a vessel’s nationality or state service.

Civil, state and naval ensigns may have different designs and eligibility rules within the same country. The ensign appropriate to the vessel is normally worn at the stern or another authorised position and identifies its flag state rather than its current location.

Display requirements, permitted variants and hours are matters of national law and custom. In the United Kingdom the Red, Blue and White Ensigns have distinct authorised uses, so colour alone should not be used to infer ownership or service without context.