Katy Perry has certainly done a lot of growing up since the release of her number one album Teenage Dream - and the stark realities she's faced are clear in Prism.

The 'Roar' hitmaker has explained that several of the songs on her new album are '100% autobiographical' and admitted to USA Today that she 'was a ball of vulnerability' while writing the tracks.

Most of the emotion came out of her devastating divorce from her husband of 14 months Russell Brand, which led to her experiencing often suicidal feelings in which she addresses in the track 'And By the Grace of God'. Her song 'Ghost' is another tune directly referring to a text that Brand said asking for a divorce. Her not so straightforward relationship with singer John Mayer also contributed to some of the pain in 'Prism', but it hasn't all been doom and gloom.

Her latest single 'Unconditionally' seems to be one of her personal favourites - a tune that she wrote while going through a short-lived break-up with John. 'To this day, it gives me goose pimples', she admitted. 'It's a pure, simple love song, a song about acceptance. I was thinking about how much I love this person. That word stuck out to me.'

She is also immensely positive on her number one single 'Roar' which is all about self-empowerment and becoming a stronger person.

Katy Perry at the MTV VMAs
Katy's empowering track 'Roar' soared to the top of the charts on its release

This time round, Katy thinks she has matured, admitting that 'Teenage Dream' was written while she was in 'a toddler state'. 'I think what 'Prism' is, is an evolution and a maturity', she told Reuters. 'I had to find own self-identity the hard way. But I did. I came out alive and stronger, a little bit stronger.'

Nowadays, she's ready to grow up a little and turns 29 on Friday (October 25th 2013). 'I've dealt with my 20s pretty good. I faced reality. I've learned from it and I'm ready to take on my 30s, which I hear are great', she tells USA Today. And just in case any of you were thinking that she might be getting a little corny with the mushy love songs and break-up ballads, Katy insists 'I don't think it's cheesy, the idea that light always wins over the darkness. People may say I'm not as cool as blah-blah-blah. I'm not afraid of that.'

Katy Perry performing at the iTunes festival
Katy is not afraid of what people think of her now