Counterpoint is the science of music. It is a musical device where two or more melodic phrases occur simultaneously. The term comes from the Latin punctus contra punctum (note against note). A note moves against another note when the interval between those two notes either grows or shrinks. By definition, chords occur when multiple notes sound simultaneously; however, this effect is considered incidental. Counterpoint focuses on melodic interaction rather than harmonic effect. The composers Palestrina, Johann Sebastian Bach, & Georg Frideric Handel frequently wrote music using counterpoint.
Generally, such music created from the Baroque period on is described as counterpoint, while music created prior to Baroque times is called polyphony. Hence, the composer Heinrich Isaac wrote polyphonic music.
The fugue offers perhaps the most complex contrapuntal convention used today in music. Other examples include the canon and ricercar.
Counterpoint is one of the most essential means, in musical composition, for the generation of musical ironies; a melodic fragment, heard alone, may make a particular impression, but when heard simultaneously with other melodic ideas, or combined in unexpected ways with itself, as in canon or fugue, surprising new facets of meaning are revealed. This is a means for bringing about development of a musical idea, revealing it to the listener as conceptually more profound than a merely pleasing melody.