The Union Flag is the flag of the United Kingdom. It is given this name because it blends the crosses of the 3 countries together into one, the kingdoms of England and Wales, Scotland and Ireland.
The flag is formed by three coats of arms crosses. The symbol of Saint George, patron-saint of England, is a red cross on a white field.
After the succession of James I, the flag of England was combined with the cross of Saint Andrew. The cross of Saint Andrew, patron-saint of Scotland, is a diagonal white cross on a blue field.
After the Act of Union of Ireland with England( and Wales) and Scotland, the cross of Saint Patrck' Saltire was combined with the previous flag. The cross of Saint Patrick' Saltire, patron saint of Ireland, is a diagonal red cross on a white ground.
On the Union Flag, the Welsh dragon does not appear. It is because, as the first Union Flag was created, the kingdom of Wales had already been merged with England and was no longer an independent kingdom.