This song finds Kesha lamenting over a lost love. The singer penned the tune with American musician Ammo, who is signed to Dr. Luke's publishing company Prescription Songs as a producer and songwriter. Ammo has also written and produced songs for Pitbull and Jordin Sparks.
Kesha told Spin magazine the song is about a former lover of hers. She explained: "'Harold' is about the only guy I've ever been in love with - and our relationship didn't work out, obviously. When I went to write it, I locked myself in a room and cried like a little bitch. I can't even listen to it. But I wanted to do a vulnerable song because it's a side of myself that people haven't seen."
Kesha refused to hide her old flame's identity with a pseudonym. The singer explained why she used Harold's actual name to Spin Magazine: "He's not getting away with a fake name. All men that date me have to know that their name may end up in a pop song. It's the best revenge: you can't get arrested for it, and everyone knows about it. And I like to be specific — I don't want any of the other losers I've dated to think the song was about them."
Kesha explained to Rolling Stone that she really did sneak into a Rolling Stones concert with Harold, which is something she got pretty good at. Said the singer: "Harold was my first boyfriend, and one of our first dates was sneaking in to see The Stones at Hollywood Bowl. I never even paid for a movie until recently. I snuck into a Strokes show and lost a shoe, but I got in there. I snuck into Coachella four years running. One year I ended up onstage with Björk. I always wear flat boots so I can climb."