Illuminati, in general without going into great detail, has to do with the elite class that basically runs the world via secret societies. It originated in Europe and Weishaupt I believe is the founder(could be wrong) and like many other things made its way to the new world. It is difficult to summarize it because it deals with a lot of information. A lot pointing towards Freemasonry and their beliefs. Plenty of books to read on it.