A canon (from Greek for “rule”) is both the simplest and the most refined polyphonic technique. The first voice begins the melody, the second enters a few bars later with the same melody, the third later still, and together they form the harmony.
The most famous canon in history is Pachelbel's Canon in D, which has become part of popular culture: used in weddings, films, and pop songs. Children around the world sing the canons Frère Jacques and Row, Row, Row Your Boat — pure canons as well.
Canons vary in complexity: in a canon at the unison the voices sing the same pitch, in a canon at the octave they enter in another register, at the fifth on a different degree, and in a riddle canon (canon enigmaticus) the composer writes only one voice and a rule of entry, inviting the performers to “solve” the piece. The Ukrainian folk tradition of ensemble singing also knows canonic entries, where the accompanying voices come in one after another.
