Canons in Bruges, Belgium.

A canon of Sint Niklaas, Flanders.

A Canon (from the Latin canonicus, itself derived from the Greek κανονικος "relating to a rule") is an honored priest who is a member of certain bodies of the Christian clergy subject to an ecclesiastical rule (canon). Originally, a canon was a cleric living with others in a clergy house or in one of the houses within the precinct or area near a cathedral, and ordering his life according to the orders or rules of the church. This way of life began to become common in the 8th century. In the 11th century, some churches required clergy living together to adopt the rule first proposed by Saint Augustine that they renounce private wealth. Those who embraced this change were known as Augustinian or regular canons, while those who did not were known as secular canons.

In the Catholic Church, specially designated clergy members of the cathedral chapter or a collegiate church are called Canons. A cathedral chapter is a special group of clergy composed to assist the bishop in the governance of his diocese. A collegiate church is a church where the community of clergy, organized as a self-governing corporate body, may be presided over by a dean. Although a collegiate church is not the seat of a bishop, and has no diocesan responsibilities, in its governance and some religious observances a collegiate church is similar to a cathedral.

Honorary canons **
The title of Canon is still given in many dioceses to senior parish priests as a largely honorary title. It is usually awarded in recognition of long and dedicated service to the diocese. Honorary canons are members of the chapter in name, but are nonresidential and receive no remuneration. They are entitled to call themselves “Canon,” and often have a role in the administration of the cathedral and the diocese (generally speaking, Canons in the Anglican or the Episcopal Church are of this sort).

They also are equivalent to a monsignor in the Catholic Church, often wearing the violet or violet-trimmed cassock which is associated with that rank. Since the reign of King Henry IV, the heads of state of France have been granted by the pope the title of sole honorary canon of Saint John Lateran.

Lay canons
In addition to canons who are clerics in holy orders, cathedrals in the Anglican Communion may also appoint lay persons as canons. The rank of "lay canon" is especially conferred upon English diocesan chancellors (the senior legal officer of the diocese, who is usually, though not exclusively, a lay person).

Secular canons
All canons of the Church of England have been secular since the Reformation, although an individual canon may himself also be a member of a religious order. Mostly, however, they are ordained, that is, priests or members of the clergy. Today, the system of canons is retained almost exclusively in connection with cathedral churches. The dean and chapter are the formal body which has legal responsibility for the cathedral and for electing the (arch)bishop.
Very Rev. Canon Tom