A song is a set of words set to music, often meant to be sung or rapped. It can be a poem, an essay or any other text that has been given melodic and rhythmic expression. The bare bones of a song consist of the lyrics and melody that are then supported by additional elements such as backing vocals, harmonies and ad libs.
It can be sung by one solo singer or a group of singers, accompanied by acoustic instruments such as guitars and pianos or orchestrated with a band or other backing musicians. It may also be used as the main music for a theatrical play, musical or opera and in television and film.
The simplest form of song structure is the verse/chorus format. This is the format typically seen in love ballads and popular rock, country and pop songs. The chorus typically repeats the same words and doesn’t differ much from the verse musically. For example Adele’s “Rolling in the Deep” and Ed Sheeran’s “Shape of You” both fit this style well.
A bridge is a section of a song that offers a break from the repetition of a chorus by changing the lyrics and music. Often the bridge will have different chords than the verse and chorus and often feature a change of pace. It can be a key element in a song to add emotional depth and variation to the story being told. There are also extended song forms such as the AABA song form and through-composed songs that use a number of different phrasing to convey a single idea over time.