A polyphonic (from the Greek for "many sounded") sound is one in which two or more melodic lines combined into a multivoiced texture, as distinct from monophonic ("one-sounding") and homophonic ("like-sounding"). The multiple musical lines may sound simultaneously, either in strict imitation of each other, or move in more independent fashion weaving in and out of each other. In the case of a musical instrument, polyphonic means the ability to play more than one note simultaneously. For example, a six-string guitar has a maximum of 6-note polyphony.
In the Western tradition, polyphony is usually distinguished from counterpoint or contrapuntal music, as exemplified by Bach's fugues. The formal style of polyphony that originated in about 900 was largely associated with religious themes, but it is likely that polyphony as a style of informal musical presentation long predates such highly stylized musical forms of European cultural expression. "Polyphony" is actually a term with a variety of uses in the context of music and music theory. It can refer to the functional capacity of certain instruments, such as some keyboards, to play more than one note at a time, but it more often refers to a musical presentation involving two or more distinct but simultaneously played tones or even chanted melodies.
The layering and texturing of melody can be seen as representative of the human condition insofar as the tapestry of human life and its meaning is difficult to communicate as single strands. Polyphony maps onto the human mind in a way similar to the phenomenon of motivation, something that is complex and fragmentary forms a coherent whole that insists on being heard. Polyphony can be seen as a contribution to pluralism, to the appreciation of valuable complimentary differences.
The joy and fervor with which music is frequently approached by practitioners is undoubtedly increased by their adding a polyphonic instrument to their repertoire. Polyphony engages the senses, and its complex tonal presentation certainly brings incomparable aesthetic benefits for the listener.