"Goodbye" is a song by Avril Lavigne, which was originally released in 2011. The song is in the key of D major. Avril Lavigne, a Canadian singer-songwriter and musician, wrote and performed the song. It was included in her fourth studio album called "Goodbye Lullaby." The track was co-written by Avril Lavigne and her then-husband Deryck Whibley. Notably, "Goodbye" was not released as a single but received positive reviews from music critics. The melody of the song is melodic and has a somewhat nostalgic tone, reflecting on themes of letting go and moving on.