Warning

The song Warning, which gives its title to Green Day's sixth album, moves away from the punk sound that characterized them. Instead, it explores more acoustic textures, with influences from pop and folk. The main guitar riff has been noted for having a similar feel to The Kinks' "Picture Book". The lyrics, written by Billie Joe Armstrong, depart from darker themes, instead presenting more optimistic and inspiring messages, something that is evident in the overall composition of the album released in October 2000.

The recording of this album, released by Reprise Records, had a different approach. While Rob Cavallo, who had produced previous works such as Nimrod (1997) and Kerplunk (1991), was involved as executive producer, the main production was handled by the band themselves. The recording engineer was Ken Allardyce, and the mixing was done by Jack Joseph‐Puig. The music video, premiered in January 2001 and directed by Francis Lawrence, portrays a carefree young man performing everyday actions, some rather unusual, throughout his day, with his time card revealing the name John Earle. Despite being a standout track, included in compilations such as International Superhits! and God's Favorite Band, and even in the video game Green Day: Rock Band, the song was not regularly played live. 21 years passed from its release in 2001 until the band performed it at a show prior to their appearance at Lollapalooza in 2022.