This is an order in Freemasonry, closely associated with Craft Freemasonry.
The first documented evidence of a ‘Royal Arch’ comes from Ireland in 1743; it seems likely that this was an ‘added extra’ worked within craft lodges in England , Ireland and Scotland for many years. Thus it came to be regarded, by the Antients in England , as a fourth degree in Freemasonry.
The Moderns, on the other hand, do not appear to have officially recognised the degree at all (with a few exceptions), leading in due course, to completely separate Royal Arch Chapters.
These differences were partially resolved at the Union of the Grand Lodges in 1813, by a compromise: the new United Grand Lodge of England declared the Royal Arch to be an official and accepted part of ‘Pure and Antient Freemasonry’.
In December 2003 the United Grand Lodge of England acknowledged and pronounced the status of the Supreme Order of the Holy Royal Arch to be
an extension to, but neither a superior nor a subordinate part of, the degrees which precede it.
Whilst the Royal Arch is, therefore, an integral part of Freemasonry and interwoven with the Craft, it is organised as a separate Order, distinct from the Craft degrees, the teachings of which it completes.