<P> "Bad Blood" is a song by American singer - songwriter Taylor Swift, from her fifth studio album 1989 (2014). Swift co-wrote the song with its producers Max Martin and Shellback, with a remixed version featuring additional writing and guest vocals from American rapper Kendrick Lamar . The Lamar version was released by Republic Records on May 17, 2015 as the fourth single from 1989 . The lyrics of "Bad Blood" describe betrayal by a close friend . The album version is the eighth track of 1989 . </P> <P> The song reached number one in Australia, Canada, Israel, New Zealand, Scotland, and the United States, becoming the third song from 1989 to do so . The accompanying music video was directed by Joseph Kahn and features an ensemble cast . The video previously held the 24 - Hour Vevo Record with 20.1 million views, before being surpassed by Adele's "Hello". It won Video of the Year and Best Collaboration at the 2015 MTV Video Music Awards . The song received a nomination for Best Pop Duo / Group Performance while its music video won Best Music Video at the 58th Grammy Awards . </P> <P> Swift co-wrote "Bad Blood" about an undisclosed female musician . Swift says the artist attempted to sabotage one of her concert tours by hiring people who worked for her . Publications such as Billboard, Rolling Stone, Time, and The Washington Post have speculated that Katy Perry is the subject of the song . Daniel D'Addario for Time and Emily Yahr for The Washington Post noted parallels between "Bad Blood" 's lyric "If you live like that, you live with ghosts" and "Ghost", a song from Perry's 2013 album Prism . The album version of the song only contains Swift as the vocalist on verses, while the single version features a re-worked instrumental and guest vocals from rapper Kendrick Lamar on verses . </P> <P> Jem Aswad of Billboard felt the song is "reminiscent of Gwen Stefani's "Hollaback Girl". The Guardian's Kitty Empire wrote that the song "faintly recalls Charli XCX with its stark beats ." It is written in the key of G major, following a chord progression of C--G--D--Em, and the tempo runs at 85 beats per minute . Swift's vocals in the song span from E to E . </P>

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