The Freemasons are a large, secular fraternal society with branches all over the world. The organization began as a trade guild of stonemasons, although as of 2015 it is largely a social and philosophical organization.
Although Freemasons are often called a secret society, they are very open about their existence and are open to new members. The details of their rituals are kept secret, but the general practices and organizational structures are well-known. Anyone can petition a lodge for membership, although most lodges only accept men. The other major requirements are showing a good moral character and demonstrating belief in a Supreme Being. However, Masons can be of any faith.
Freemasons are often the subject of conspiracy theories. This is in part because many high-ranking figures in history have belonged to the organization. The Catholic Church and other authorities have also been opposed to the Freemasons throughout history. This was mostly due to the secular nature of the group, which seeks moral authority and enlightenment outside of the Church. In addition, conspiracy theorists point to some Masonic symbols that adorn government buildings and other objects. The eye in the pyramid on the back of a U.S. dollar bill is one example. These symbols are widespread in part because many prominent people were Masons, and also because the Freemasons used popular everyday symbols to develop their rituals.