Counterpoint was an musical style that comprised of combining different melodic lines, and shaped Western musical elements.  Often, this term is interchanged with the word polyphony, but counterpoint is a more specific use of multiple melodic lines whereas polyphony only refers to the presence of multiple melodies.  During the Renaissance, many composers focused their efforts on imitation, or the successive statement of similar melodies in each of the voices. Often, to ensure a clear relation between the two voices, the composers would have the two voices sing together and be separated by a certain interval.  This was also the beginning of the popularization of canon, which is a musical form that has imitated parts throughout the piece.