Freemasonry is a fraternal organisation that uses the tools and traditions of the medieval stonemason's craft as a system of moral and philosophical teaching. It initiates members through a series of degrees — ceremonial rituals that convey ethical lessons through allegory and symbol — and organises its members into local groups called Lodges, which are governed by Grand Lodges at the national or regional level.
The modern institution traces its official founding to 1717, when four London tavern lodges united to form the Premier Grand Lodge of England. Its actual origins are contested. The most credible historical view is that it emerged from the operative stonemasons' guilds of medieval Britain — craftsmen who built the great cathedrals and who maintained trade secrets, passwords and recognition signals to identify qualified workers. At some point in the 17th century these guilds began admitting speculative (non-operative) members: gentlemen, intellectuals and philosophers interested in the symbolic and philosophical dimensions of the craft rather than the practical ones.
What Freemasonry is not: it is not a religion (though it requires belief in a Supreme Being and uses religious imagery); it is not a political organisation (lodges officially prohibit political discussion); it is not a secret society in the sense of concealing its existence — the organisation is publicly known and most Masons openly identify as such. What is kept private are the ritual details, passwords and recognition signals used between members.
At its core, Freemasonry teaches a system of moral philosophy organised around the classical virtues: brotherly love, relief (charity) and truth. The craft metaphor runs throughout — the rough ashlar (unworked stone) represents the uninitiated self; the perfect ashlar (smooth, dressed stone) represents the self refined by moral work. The working tools of the mason — the gavel, the square, the compasses, the level — each carry ethical meaning. It is, in essence, an elaborate and ancient system for teaching virtue through symbol and ceremony.