Music is an art that, in one guise or another, permeates every human society. Modern music is heard in a bewildering profusion of styles, many of them contemporary, others engendered in past eras. Music is a protean art; it lends itself easily to alliances with words, as in song, and with physical movement, as in dance. Throughout history, music has been an important adjunct to ritual and drama and has been credited with the capacity to reflect and influence human emotion. Popular culture has consistently exploited these possibilities, most conspicuously today by means of radio, film, television, musical theatre, and the Internet. The implications of the uses of music in psychotherapy, geriatrics, and advertising testify to a faith in its power to affect human behaviour. Publications and recordings have effectively internationalized music in its most significant, as well as its most trivial, manifestations. Beyond all this, the teaching of music in primary and secondary schools has now attained virtually worldwide acceptance.