X (pronounced ten) is the eighth studio album by English rock band Def Leppard, released on 30 July 2002 by Island Records in the US and sister label Mercury worldwide. Much like 1996’s Slang, it featured another departure from their signature sound by moving into the pop genre. The album charted at No. 11 on The Billboard 200 and No. 14 on the UK Albums Chart. Most of the album was produced by Pete Woodroffe and the band, with remaining tracks produced by either Marti Frederiksen or Per Aldeheim and Andreas Carlsson. This is the first Def Leppard album in which drummer Rick Allen actively took part in song-writing. On all of the band’s prior albums, he is only credited with helping co-write three tracks. On this album alone, he co-wrote eleven.
The album features the Roman numeral ’X’, recognising it as their tenth album release, although the album is in fact only their eighth collection of all-new studio material. The other two albums released by the band prior to the release of X, Retro Active and Vault, were a rerecording of B-sides and rarities and a greatest hits set respectively.
The album peaked at number 11 on the Billboard 200, but did not sell to the standards of their previous releases and failed to earn any RIAA certifications. With the exception of an abbreviated version of ”Now” being performed as part of an acoustic medley during the ’Rock of Ages’ tour in 2012, nothing from this album has been performed live by the band since the conclusion of its supporting tour.