Also known as the Union Flag, it is the name given to the national flag of the United Kingdom. It is a combination of three different flags: the red St. George's Cross of England, the white St. Andrew's Cross of Scotland, and the red St. Patrick's Cross of Ireland.
Technically speaking, a jack is a flag displayed by a ship, so the name "Union Jack" is incorrect when the Union Flag appears in any other context, but popular usage, as is so often the case, defeats technical correctness in everyday life.
The design of the Union Jack consists of a blue field, known as the Union Flag, with a red diagonal cross (St. Patrick's Cross) that extends from corner to corner. This cross represents Ireland. Superimposed on the diagonal cross are two intersecting crosses. The upright red diagonal cross (St. George's Cross) represents England, and the white diagonal cross in the shape of an "X" (St. Andrew's Cross) represents Scotland.
The Union Jack's design was first created in 1606 when England and Scotland were separate kingdoms but shared the same monarch, King James VI of Scotland and I of England. The flag was officially adopted in 1801 after the Act of Union, which united the Kingdom of Great Britain (combining England and Scotland) with the Kingdom of Ireland.
Also appears in the national flags of Australia, New Zealand, Fiji, and Tuvalu, as well as those of British colonies and territories. It is also on the flag of the American state of Hawaii.
This may be confused with a mecha from Gundam 00 called a Union Flag used by the world superpower Union in the series.
