Freemasonry or Masonry consists of fraternal organisations that trace their origins to the local fraternities of stonemasons that from the end of the fourteenth century regulated the qualifications of stonemasons and their interaction with authorities and clients.

The degrees of Freemasonry retain the three grades of medieval craft guilds, those of Apprentice (Entered Apprentice), Journeyman or fellow (now called Fellowcraft), and Master Mason. The candidate of these three degrees is progressively taught the meanings of the symbols of Freemasonry, and entrusted with grips, signs and words to signify to other members that he has been so initiated.

The initiations are part allegorical morality play and part lecture. The three degrees are offered by Craft (or Blue Lodge) Freemasonry. Members of these organisations are known as Freemasons or Masons. There are additional degrees, which vary with locality and jurisdiction, and are usually administered by their own bodies (separate from those who administer the craft degrees).

The basic, local organisational unit of Freemasonry is the Lodge or Blue Lodge as it is sometimes called. The Lodges are supervised and governed at the regional level by a Grand Lodge. There is no international, worldwide Grand Lodge that supervises all of Freemasonry; each Grand Lodge is independent.

Freemasonry is a "'beautiful system of morality, veiled in allegory and illustrated by symbols". The symbolism is mainly, but not exclusively, drawn from the manual tools of stonemasons – the square and compasses, the level and plumb rule, the trowel, among others. A moral lesson is attached to each of these tools, although the assignment is by no means consistent. The meaning of the symbolism is taught and explored through ritual.

All Freemasons begin their journey in the "craft" by being progressively "initiated", "passed" and "raised" into the three degrees of Craft, or Blue Lodge Masonry. During these three rituals, the candidate is progressively taught the meanings of the Lodge symbols, and entrusted with grips, signs and words to signify to other Masons that he has been so initiated. The initiations are part allegory and part lecture, and revolve around the construction of the Temple of Solomon, and the artistry and death of his chief architect, Hiram Abiff. The degrees are those of "Entered apprentice", "Fellowcraft" and "Master Mason". While many different versions of these rituals exist, with at least two different lodge layouts and versions of the Hiram myth, each version is recognisable to any Freemason from any jurisdiction.

The idea of Masonic brotherhood probably descends from a 16th-century legal definition of a "brother" as one who has taken an oath of mutual support to another. Accordingly, Masons swear at each degree to keep the contents of that degree secret, and to support and protect their brethren unless they have broken the law. In most Lodges the oath or obligation is taken on a Volume of Sacred Law, whichever book of divine revelation is appropriate to the religious beliefs of the individual brother (usually the Bible in the Anglo-American tradition, but all lodges posesse a Quran and a Tanach should they be required).