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.
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 white diagonal crosses. The upright white diagonal cross (St. George's Cross) represents England, and the 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.