U2 are giving away their 13th studio album for free.

The Irish rockers - made up of Bono, The Edge, Adam Clayton and Larry Mullen Jr - have made their latest offering 'Songs Of Innocence' available cost-free to over a half a billion U2.com subscribers and all iTunes Music Store customers.

The autobiographical record features collaborations with Ryan Tedder, Lykke Li, Danger Mouse and Paul Epworth and is intended to reflect the band's varying styles and influences over the decades.

The album kicks off by paying homage to the early influence of The Ramones on the band in their track 'The Miracle', before revisiting a Clash gig they attended in 1977 in 'This Is Where You Can Reach Me'.

'California' is a nod to The Beach Boys, while 'Song for Someone' was written for the rockers by Bono's wife, Ali, whom he met when he was just 12-years-old, reports The Daily Star newspaper.

It is also thought the band will play a series of smaller gigs in place of their usual arena shows to go along with the album's physical release on October 13.