A canon is a well-established set of principles, rules, or standards that are followed and recognized within a particular context, such as religion, literature, or music. In music, a canon is a compositional technique where a melody is imitated by one or more voices or instruments at a fixed interval of time. This creates a layered and harmonious sound that is characteristic of a canon. Canons have been used in many famous works, such as Johann Pachelbel's Canon in D and the rounds "Row, Row, Row Your Boat" and "Frère Jacques." The term "canon" can also refer to a list of authoritative texts or works that are considered essential or representative in a particular field or subject. In the context of religion, canon can also refer to the official collection of sacred texts accepted as genuine and authoritative.