An ensign is the national flag flown on a vessel to indicate nationality. The ensign is the largest flag, generally flown at the stern (rear) of the ship while in port. The naval ensign, used on warships, may be different from the civil ensign or the yacht ensign. Large versions of naval ensigns called battle ensigns are used when a warship goes into battle. The ensign differs from the jack, which is flown from a jackstaff at the bow of a vessel.
