Mark Henderson answered
An outro in music means the ending of the song, although the term can also be used to refer to the concluding track of an album.
Like the intro of a song (the beginning of the arrangement), the outro adds a dimension to the arrangement which lets the listener know the song is beginning to end.
The outro (like the intro) should also depend on the mood and feel of the song. If a composer has composed an aggressive song, then it is more likely that the song will end with an aggressive outro. Likewise if the song is a slow melodic ballad then the outro may slowly fade out rather than coming to an abrupt end.
The term is only typically used in reference to pop music, and not all songs have an outro. Instead, the composer may choose to end the song on another part of the arrangement - such as the chorus or verse.
Sometimes composers use solos in the outro to their arrangements, usually guitar solos. Songs with famous solo-outros include: "Black Dog" by Led Zeppelin, Eric Clapton's "Layla", Pink Floyd's "Comfortably Numb", "Hotel California" by Eagles and Metallica's "Fade to Black".
Typical Pop Song Arrangement
Intro
Verse
Chorus
Verse
Chorus
Breakdown/Bridge
Chorus
Outro
Like the intro of a song (the beginning of the arrangement), the outro adds a dimension to the arrangement which lets the listener know the song is beginning to end.
The outro (like the intro) should also depend on the mood and feel of the song. If a composer has composed an aggressive song, then it is more likely that the song will end with an aggressive outro. Likewise if the song is a slow melodic ballad then the outro may slowly fade out rather than coming to an abrupt end.
The term is only typically used in reference to pop music, and not all songs have an outro. Instead, the composer may choose to end the song on another part of the arrangement - such as the chorus or verse.
Sometimes composers use solos in the outro to their arrangements, usually guitar solos. Songs with famous solo-outros include: "Black Dog" by Led Zeppelin, Eric Clapton's "Layla", Pink Floyd's "Comfortably Numb", "Hotel California" by Eagles and Metallica's "Fade to Black".
Typical Pop Song Arrangement
Intro
Verse
Chorus
Verse
Chorus
Breakdown/Bridge
Chorus
Outro