Counterpoint in Reading Music
Counterpoint is a basic element of musical composition found when two or more melodies are played at the same time. It's used in nearly every composition, even popular ones. The counterpoint in a rock composition would be the lead vocals against the lead guitar, or the lead keyboards against the bass keyboards in an electronic composition. But it's rare to hear it described as a counterpoint in these situations; it's generally just referred to as a separate part. Counterpoint truly becomes counterpoint in classical fugues and canons, where the layering and shadowing of melodies is the very key to the composition. It's important to note, however, that counterpoint is only applicable to melodic elements; rhythmic elements, while adding a counterpoint to the other instruments in some respect, is not technically considered to be providing a counterpoint.
There exist various ways to create a counterpoint in classical composition, but the most common are retrograde, augmentation, diminution, inversion and dissonance. Creating a counterpoint based on these concepts is fairly simple in the text. A retrograde counterpoint is one in which the following melody is played backwards from the original melody; an augmentation counterpoint is one in which the original melody's notes are lengthened. Likewise, a diminution counterpoint is one in which the original melody's notes are shortened. A counterpoint inversion is one in which the intervals in the following melody are played opposite to the lead melody; this type of counterpoint can also be combined to create an inverted retrograde, playing the following melody backwards by both structure and interval. Finally, a dissonance counterpoint is one that is made dissonant, one that turns the consonant chords into dissonant ones; this is by far the most complicated type of counterpoint.