"Not the End of the World" is a song by American singer Katy Perry from her sixth studio album Smile (2020). It was released on December 21, 2020, by Capitol Records as the third single from the album. It was written by the singer, Michael Pollack, Madison Love, Jacob Kasher Hindlin, and Andrew Goldstein, and was produced by Goldstein and Oscar Görres. Built off the interpolation of a melody from Steam's 1969 song "Na Na Hey Hey Kiss Him Goodbye", it is a techno-pop and trap-pop track with an underlying disco and techno beat. A self-empowerment cut, with the lyrics about positivity and Perry's indifference to her critics. Compared to her 2013 single "Dark Horse", the song left music commentary divided. Some of them depreciated the single's message in the context of the COVID-19 pandemic.

"Na Na Hey Hey Kiss Him Goodbye" is a 1969 song written and recorded by Paul Leka, Gary DeCarlo and Dale Frashuer, attributed to a then-fictitious band Steam. It was released under the Mercury subsidiary label Fontana and became a number-one pop single on the Billboard Hot 100 in late 1969, and remained on the charts in early 1970.