Harmony refers back to the "vertical" sounds of pitches in music, which implies pitches which are performed or sung with each other simultaneously to make a chord. Generally, This suggests the notes are performed simultaneously, although harmony may be implied by a melody that outlines a harmonic structure (i.e., by https://emmaklewis.sites.gettysburg.edu/scalar/saliman/an-easy-way-to-download-old-school-songs-via-the-internet.html