Popular music is music that can typically be enjoyed, and often performed, by people with relatively little formal musical training. In contrast to classical music, people usually learn to play by it by listening rather than from reading sheet music. Audiences are usually far larger than for classical music, and it is propagated through the music industry.
Popular songs are usually brief, with most of them being under four minutes, whereas classical compositions can range from less than a minute to several hours. In addition, whereas popular music is mostly vocal, classical music is mostly instrumental, and even in the case of opera the instrumental component plays a very important role.
The distinction between popular music and classic music is not always clear, particularly in the case of contemporary art music. While it is frequently described by its advocates as contemporary classical music because it often shares the above criteria with classical music, others contend that it is too different from classical music to be put in the same category despite these similarities and that much of it is at least just as closely related to popular music.