The Ancient and Accepted Scottish Rite of Freemasonry, commonly known as simply the Scottish Rite is one of several Rites of Freemasonry. A Rite is a progressive series of degrees conferred by various Masonic organizations or bodies, each of which operates under the control of its own central authority. In the Scottish Rite the central authority is called a Supreme Council.

The Scottish Rite is one of the appendant bodies of Freemasonry that a Master Mason may join for further exposure to the principles of Freemasonry. It is also concordant, in that some of its degrees relate to the degrees of Symbolic (Craft) Freemasonry. In England and some other countries, while the Scottish Rite is not accorded official recognition by the Grand Lodge, only a recognised Freemason may join and there is no prohibition against his doing so. In the United States, however, the Scottish Rite is officially recognized by Grand Lodges as an extension of the degrees of Freemasonry. The Scottish Rite builds upon the ethical teachings and philosophy offered in the Craft (or Blue) Lodge, through dramatic presentation of the individual degrees.

https://en.wikipedia.org/wiki/Scottish_Rite