Katy Perry

One of the Boys in 2008 introduced the version of Perry that reached a worldwide audience. “I Kissed a Girl” carried the provocation, “Hot n Cold” supplied a quick-fire argument and “Thinking of You” showed the more conventional songwriter underneath. Guitars still had a prominent role, giving the early singles a sharper edge than the electronic pop that followed.

Teenage Dream, released in 2010, was the decisive expansion. “California Gurls”, the title track, “Firework” and “Last Friday Night (T.G.I.F.)” each built a whole scene around an immediate chorus. The record is unusually clear about its emotional colours: euphoria, embarrassment, attraction and disappointment are all allowed to be large.

Prism in 2013 kept the big hooks but changed the balance. “Roar” is built for collective release, while “Dark Horse” leaves more space around a lower, slower beat. Later records kept moving through electronic pop, but the most durable quality is not a particular production sound. It is the singer’s ability to make a line feel conversational just before the chorus makes it enormous.

The albums are most rewarding when the playful singles sit beside the more exposed songs. Perry is often remembered through visual ideas, yet the music has its own firm architecture. A strong opening phrase, an unambiguous melody and a sense of lift do a great deal of the work before the video begins.