Lyrics are words that make up a song, usually consisting of verses and choruses. The writer of lyrics is a lyricist. The words to an extended musical composition such as an opera are, however, usually known as a "libretto" and their writer, as a "librettist". Rap songs contain rap lyrics that are meant to be spoken rhythmically rather than sung. The meaning of lyrics can either be explicit or implicit. Some lyrics are abstract, almost unintelligible, and, in such cases, their explication emphasizes form, articulation, meter, and symmetry of expression.

A song is a musical composition performed by the human voice. The voice often carries the melody using patterns of sound and silence. Songs have a structure to them, such as the common ABA form, and are usually made of sections that are repeated or performed with variation later. A song without instruments is said to be a cappella.