A crude form of communication based upon patterned oscillating atmospheric distortions generated via vocal and or instrumental means with the intent to convey some emotion or express some (typically abstract) concept. Music exist in several different genres, which can be further subdivided into smaller classifications; but those are mostly created by marketing reps to confuse the average listener and incite rivalry amongst unimportant subcultures. The bottom line is trends and the all mighty $. Whatever values coveted by the factions who vehemently enjoy one particular type of music over another are not truly relevant.
For some reason music seems to speak to the soul of most people. It reaches out to the primal man-ape within us all. The weak minded can be controlled or inspired by it. An impressionable music aficionado can be persuaded or dissuaded to kill his or her best friend just by listening to music. Music can be soothing riveting or something all together different.