How did canon use imitation between different musical parts?

In Western music, a canon is a compositional technique based on the principle of strict imitation, where an initial melody is repeated by one or more parts at a specified time interval.1

The imitation between parts functions through several methods:

• Pitch and Timing: The imitating part may enter at the same pitch (the unison) or at a different pitch level. The imitation can occur using the same note values, or through augmentation (longer note values) and diminution (shorter note values).1
• Melodic Alteration: The original melody can be manipulated during imitation. It may be played backward (retrograde), inverted so the intervals move in the opposite direction (mirror), or both (retrograde mirror).1
• Complexity: Canons can range from simple rounds, where the melody is identical, to complex structures like the mensuration canon, where parts proceed simultaneously at different rates of speed.12

While imitation is the defining feature of a canon, it also served as a broader unifying device in Renaissance polyphony, where it helped establish equality among voice parts.23