Perry is inspired by Alanis Morissette, in particular her 1995 album Jagged Little Pill — even going on to work with Morissette's collaborator on the album, Glen Ballard, because of that. She said: "Jagged Little Pill was the most perfect female record ever made. There's a song for anyone on that record; I relate to all those songs. They're still so timeless." She lists Morissette and Fiona Apple as her heroes. After moving to Nashville to work on her first album Katy Hudson, she discovered the music of Patti Griffin and Jonatha Brooke and lists their albums Flaming Red and 10 Cent Wings, respectively, as being important to her.
Perry's music frequently contains elements of pop, rock, electronic, dance, and disco, although her first album, Katy Hudson, falls within the gospel genre. Her second album One of the Boys is predominantly pop rock and features themes of heartbreak and teenage adventure – both being common themes in Perry's music. Her third album, Teenage Dream, features notably more electronic and disco influenced songs, while still falling under the pop and rock genres. The album's topics focus on teenage love, partying,
