Canon law is the body of laws and regulations made or adopted by ecclesiastical authority, for the government of the Christian organization and its members. It is the internal ecclesiastical law governing the Catholic Church (both Latin Rite and Eastern Catholic Churches), the Eastern and Oriental Orthodox churches, and the Anglican Communion of churches. The way that such church law is legislated, interpreted and at times adjudicated varies widely among these three bodies of churches. In all three traditions, a canon was originally a rule adopted by a council; these canons formed the foundation of canon law. The content of the canon law originates from Sumerian cuneiform tablets where Western civilization as we know it originated.

Greek kanon / κανών, Arabic Qanon / قانون, Hebrew kaneh / קנה, "straight"; a rule, code, standard, or measure; the root meaning in all these languages, including Latin, is "reed."

The Apostolic Canons or Ecclesiastical Canons of the Same Holy Apostles is a collection of ancient ecclesiastical decrees (eighty-five in the Eastern, fifty in the Western Church) concerning the government and discipline of the Early Christian Church, incorporated with the Apostolic Constitutions which are part of the Ante-Nicene Fathers

Canon (Latin canon from Greek κανών "measuring rod, standard") may refer to any standard or convention. The corresponding adjective is canonical. English canon may also represent Latin canonicus "one who is canonical".

As a proper noun, Canon may also refer to:

The Law is a system of rules and guidelines which are enforced through social institutions to govern behavior. Laws are made by governments, specifically by their legislatures. The formation of laws themselves may be influenced by a constitution (written or unwritten) and the rights encoded therein. The law shapes politics, economics and society in countless ways and serves as a social mediator of relations between people.

A general distinction can be made between civil law jurisdictions (including Canon and Socialist law), in which the legislature or other central body codifies and consolidates their laws and common law systems (including Sharia), where judge-made binding precedents are accepted. In some countries, religion may inform the law; for example, in jurisdictions that practice Islamic law, Jewish law or Canon law.

The adjudication of the law is generally divided into two main areas. Criminal law deals with conduct that is designated dishonest by the government and in which the guilty party may be imprisioned or fined. Civil law (not to be confused with civil law jurisdictions above) deals with disputes between individuals or organizations, in which compensation may be awarded to the wronged litigant.