The word canon has several meanings in different areas.

Table of contents
1 In religion
2 In literature and art
3 In music
4 In photography

In religion

A canon in one sense is a rule adopted by a Council of the Catholic or Eastern Orthodox churches. From Greek kanon, for rule or measure. See canon law.

It is also a rank in the Christian church; canons are priests who are specifically attached to a cathedral and have responsibility for some aspect of its running.

In another sense, a canon is a list of books accepted by a religion as authoritative or divinely inspired. The term was originally Christian, referring to books declared divinely inspired by the canons of Church councils. The term has however come to be extended to other religions as well with compound scriptures, thus one can speak for instance of the Pali canon in Buddhism. See biblical canon for a discussion of the canon of Christianity.

In one final sense, a canon is a member of religious group or a person holding a position of authority (prelate) in some Christian faiths.

Canon is also what is prescribed as the only correct way to paint an icon or a fresco.

In literature and art

In usually academic, non-religious contexts, the so-called Western canon is often spoken of. This is a body of literature and art recognized as definitive of Western civilization.

In non-academic, non-religious contexts, canon is used to describe works of fiction that represent "official" records of events in particular fictional settings. For example, in Star Trek, the various live-action television series and movies are considered to be canon whereas the Star Trek novels and cartoon series are not. Events which occur in non-canon works of fiction are not considered a part of the continuity of the rest of the series, and can be disregarded freely by authors and readers alike when considering the setting as a whole. The criteria for deciding whether a particular work of fiction is considered to be canonical for a particular setting or not varies, sometimes being dictated by a particular authority (often a copyright or trademark holder) and sometimes being decided by informal consensus among those who care. Harry Potter fans consider only things stated by J. K. Rowling, herself, canon. Therefore the Harry Potter books, Quidditch Through the Ages and Fantastic Beasts and Where to Find Them are considered canon, whereas the films and other material released by Warner Bros are not.

In music

see: Canon (music)

In music, a canon is a contrapuntal composition that employs a melody with one or more imitations of the melody played after a given duration (e.g. quarter rest, one measure, etc.). The initial melody is called the leader, while the imitative melody is called the follower which is played in a different voice. The follower must be created from the leader by being either an exact replication of the rhythms and intervals of the leader, or a transformation such as those listed in "types of canons" (below). The simplest and most familiar examples are rounds such as Row, Row, Row Your Boat.

In photography

Canon is also the name of a Japanese company that specialises in imaging and optical products.