"Really Don't Care" is a song by American recording artist Demi Lovato, featuring English recording artist Cher Lloyd. The song was released on May 20, 2014, as the fourth single from her fourth studio album Demi (2013). It was written by Lovato and Lloyd along with Carl Falk, Savan Kotecha and Rami Yacoub, and was produced by Falk and Yaboub. It accumulated the most views of all the songs Lovato streamed from the album prior to its release, and was also the best-selling non-single from Demi. Upon the album's release, "Really Don't Care" received praise from critics and was cited as a potential single choice by Billboard. "Really Don't Care" is Lovato's third number one on the US Dance chart. 
Cher Lloyd co-wrote her verse, and is the album's only featured guest.
"Really Don't Care" is an uptempo dance-pop song, with influences of bubblegum pop, that runs for three minutes and twenty-one seconds. Lyrically, the song is a message of defiance to a former lover, with Lovato confidently singing such lines as "Even if the stars and moon collide, I never want you back into my life." The song was written in the key of G major. Lovato originally wrote the song as a breakup song. She wanted to make it a more empowering song. Lovato said in an interview, "I wanted to make it more empowering. When I thought of the lyrics 'really don’t care', it made me think of bullying, and made me think of the LGBT community, who deal with that so often, but they accept themselves."
Upon its release, "Really Don't Care" has garnered mostly positive reviews. Adrienne Erin of Star Pulse called "Really Don't Care" a "rocking" dance hit, and noted that Lovato's "angsty" vocals "show that she means business"; she declared it her favorite song from Demi.Billboard writer Jason Lipshutz praised Lovato's sassy confidence on the track, which effectively showcases her "overpowering pipes". He also commented positively on the placement of the song on the track list, noting that "Really Don't Care" serves a "buoyant repreive" after more emotionally-heavy tracks. Sam Lansky of Idolator described the song as "irresistibly spunky", but found Lloyd's short feature to be superfluous.4Music called the song "a brilliant break-up survival anthem that sticks it to every annoying ex ever". On the other hand, Melinda Newman of HitFix found the song to be too generic, comparing it to Icona Pop's breakout hit "I Love It" (2012).
The official music video was released on June 26, 2014, although few teasers for the video were previously uploaded on Lovato's official YouTube channel. The video starts off with Demi expressing her support for the LGBT community and saying that "[her] Jesus loves everyone." After that, the music starts and Lovato is seen singing her single at the parade. The video was filmed on June 8, 2014 at the LA Pride Parade and features cameo appearances from Perez Hilton, Kat Graham, Shane Bitney Crone, Bria Kam and Chrissy Chambers,John Taylor, Travis Barker and Wilmer Valderrama. Cher Lloyd also appears during the bridge part of the song. The video was directed by Ryan Pallotta.
The lyric video was released on May 14, 2014. The video features the lyrics of the song above several shots of Brazilian fans lip syncing the song as well as some scenes from concerts where Lovato performs the song during the concert tour. During the video, Lovato makes an appearance to surprise some of the fans. At the end, a message is displayed to thank the Brazilian fans for helping out with the filming of the lyric video.