A song is a combination of melody, lyrics and harmony. It usually has structure, repetition of verses and choruses.
Song is a genre of music in which a voice is combined with words to convey a poem or other literary work. It can be performed alone, or with accompaniment from instrumentalists.
Singing, a form of oral communication, has been complemented by the use of musical instruments from earliest times; music heightens the effect of speech, giving the singer a projection and passion that is difficult to attain without an instrument. The singing style varies from culture to culture, reflecting such factors as the ideals of social interaction and perceptions of the spirit world.
Art songs, also called lieder, have their origins in the medieval courts, colleges and cities of Europe; the texts and melodies are sophisticated and often wide-ranging. These are primarily intended for performance by professional or at least carefully taught singers, accompanied by piano or other instrumental ensemble.
Folk songs, which are often sung to traditional music and folk dances, can also be distinguished from the more serious art song. Unlike the more technical nature of art songs, folk songs are often connected with extramusical activities, such as religious ceremonies, dances and labour.
Popular songs, by contrast, are sung to more familiar material, and stand midway between folk and art songs in terms of technical difficulty and complexity of the musical structure. These songs may be sung by amateur or semi-professional singers, accompanied by instrumentalists, or played on a recording or live performance.