Canon is a word used in many fields to indicate a rule, a standard, or a recognised collection of items. It often carries a sense of authority, regularity or exemplary status: a canon can be a law or principle, a list of sacred texts, a member of a cathedral chapter, a compositional technique in music, or a standard form in technical disciplines.

Etymology and historical outline

The term comes from Greek kanon, originally meaning a measuring rod or rule, and passed into Latin and later European languages with related senses. Early religious communities applied it to rules of faith and to lists of authoritative scriptures; over time the notion expanded to law, liturgy, literary taste and technical standards.

Main senses

  • Religious and biblical: "the canon" commonly denotes the set of books a religious tradition accepts as scripture. Different communities have produced different canonical lists and have treated other texts as apocryphal or noncanonical.
  • Canon law: laws, norms and regulations developed by ecclesiastical bodies to govern doctrine, worship and organisation.
  • Clerical office: a canon is a clergy person who belongs to the chapter of a cathedral or collegiate church, with liturgical and administrative duties; distinctions are drawn between secular and regular canons.
  • Arts and literature: the literary or artistic canon means works widely regarded as exemplary or central to a tradition; debates over canons concern inclusion, representation and changing standards.
  • Music: a canon is a contrapuntal form in which a melody is imitated after a delay by one or more voices, producing strict or free imitation; rounds and other imitative pieces exemplify this technique.
  • Popular culture: in media franchises and fandoms "canon" denotes material officially part of a work's continuity, in contrast with fan-created "fanon" or noncanonical variations.
  • Science and technical use: "canonical" refers to a standard, simplest or preferred form of an object or representation (for example canonical forms in mathematics, canonical URLs or canonicalization in computing).

Canons shape education, identity and institutional practice by signalling authority or exemplary status. In humanities and media, controversies over the canon centre on who decides what is included and whether the canon reflects diverse voices. In religion, canonical lists determine which texts guide doctrine and worship and which are viewed as apocryphal. The adjective "canonical" may be used descriptively (widely recognised) or prescriptively (ought to be recognised).

Common confusions include the near-homophone "cannon" (a large gun), which is unrelated in meaning. Because canonicity often reflects historical power and evolving standards, what a community accepts as canonical can and does change over time as scholarship, practice and values develop.