
Kurstin recalled, "I rethought the music part of it, I guess. Aldrich had then commissioned Greg Kurstin, whom Clarkson wanted to collaborate with, to produce and add additional writing to the final version. Tamposi revealed that Clarkson had also altered a lyric from the track. Tamposi's manager, Tom Maffei, then had one of his producers, Matty Trump, produce a demo track, later pitched to RCA A&R executive Jeff Aldrich, who gave the song to Clarkson. Elofsson originally intended "Stronger" for Leona Lewis, who turned it down in the process. Although Tamposi found the phrase saccharine, she submitted it as an idea to Elofsson and Gamson during their writing sessions. In an interview with American Songwriter, Tamposi revealed that the song was inspired by the Friedrich Nietzsche adage ("That which does not kill us makes us stronger") that her mother told her as advice. Originally titled as "What Doesn't Kill You", "Stronger (What Doesn't Kill You)" was written by Jörgen Elofsson, Ali Tamposi, David Gamson, and Greg Kurstin in September 2010. Clarkson also included the song in the set list of her Stronger Tour and on the encore set of her 2012 Summer Tour with The Fray.

With its continued success, she performed "Stronger" on several live award shows and television appearances around the world, debuting it during the first season of The X Factor (US) and performing it on the 37th season of Saturday Night Live, the 2012 MuchMusic Video Awards, and the 2012 American Music Awards. It earned Clarkson a nomination for a MuchMusic Video Award. The music video garnered positive reception from critics who felt that its overall impact was exuberant. The song's accompanying music video was filmed by Shane Drake, which incorporates the theme of a global flash mob dance, featuring submitted videos of people dancing to the song. "Stronger" merited consideration for several industry awards-including three Grammy Award nominations, and a World Music Award nomination. Its success helped its parent album to sustain commercial longevity for over a year.

Internationally, "Stronger" topped the national charts of Poland, Slovakia, and Slovenia and attained a top-ten position in over fifteen countries around the world, eventually selling over five million copies worldwide. It also topped fifteen other Billboard charts, including Adult Pop Songs, Adult Contemporary, Hot Dance Club Songs, and Pop Songs charts, more than any other song Clarkson has ever released. In the United States, "Stronger" became her third song to top the Billboard Hot 100 chart for three non-consecutive weeks, surpassing " A Moment Like This" (2002) and " My Life Would Suck Without You" (2009) as her longest-running number-one single on the chart. Its lyrical content mainly explores themes of empowerment and recovery following a heartbreak, with the chorus inspired by a Friedrich Nietzsche quotation: "That which does not kill us makes us stronger." Written by Jörgen Elofsson, Ali Tamposi, and David Gamson, with additional writing and production by Greg Kurstin, "Stronger (What Doesn't Kill You)" is an uptempo song which draws from the genres of dance-pop and electropop. Originally titled as "What Doesn't Kill You (Stronger)", the song served as the album's second single on January 17, 2012, through RCA Records. " Stronger (What Doesn't Kill You)" is a song by American recording artist Kelly Clarkson and the title song from her fifth studio album, Stronger (2011).

"Stronger (What Doesn't Kill You)" on YouTube
