Biffy Clyro are a Scottish rock band that formed in Kilmarnock, East Ayrshire, composed of Simon Neil (guitar, lead vocals), James Johnston (bass, vocals) and Ben Johnston (drums, vocals). Currently signed to 14th Floor Records, they have released seven studio albums, four of which (Puzzle, Only Revolutions, Opposites and Ellipsis) reached the top five in the UK Albums Chart, with their sixth studio album, Opposites claiming their first UK number-one album. After their first three albums, the band expanded their following significantly in 2007 with the release of their fourth, Puzzle, creating more mainstream songs with simpler rhythms and distancing themselves from the more unusual dissonant style that was present in their previous three albums. Puzzle peaked at number 2 on the official UK album charts on 16 June 2007.

On 9 April 2001, the previously unreleased "27" was released as a single. On 1 October 2001, a song from thekidswho... was re-recorded and released as a single, "Justboy"; this was repeated again on 4 February 2002, when the song "57" was released. On 11 March, the band's debut album, Blackened Sky, was released to generally positive reviews. It was around this time that the band began touring extensively, including supporting Weezer on 20 March at the Barrowlands in Glasgow. On 15 July, the fourth single from the album, "Joy.Discovery.Invention", was released as a double A-side with a newly recorded song called "Toys, Toys, Toys, Choke, Toys, Toys, Toys" (which would later also appear on their next album The Vertigo of Bliss).  In 2003, the band retreated to the Linford Manor recording studio in Great Linford, Milton Keynes, England, to record the follow-up to Blackened Sky. On 24 March, a new single was released called "The Ideal Height", followed by a further new single "Questions and Answers" on 26 May. The band's second album, The Vertigo of Bliss was released on 16 June, to positive reviews which focused on the more experimental style of the album in comparison to Blackened Sky, as well as the introduction of string sections.  After touring relentlessly for The Vertigo of Bliss, the band retreated to Monnow Valley Studio in Monmouth, Wales to record a follow-up album. As with the previous album, two singles were released before the actual album: "Glitter and Trauma" and "My Recovery Injection" on 9 August and 20 September respectively. An additional digital download was also released on 31 May, called "There's No Such Thing As A Jaggy Snake". On 4 October, the band's third album, Infinity Land was released, followed by the final single from the album, "Only One Word Comes To Mind", on 14 February 2005. On 16 February, the band performed a cover of Franz Ferdinand's "Take Me Out" live from Maida Vale on Zane Lowe's BBC Radio 1 show.  Simon Neil's side project Marmaduke Duke also released an album in 2005, known as The Magnificent Duke. He toured the UK together with the Johnston twins accompanying on bass and drums.

Answer the following question by taking a quote from the article: What was Blackened Sky?
the band's debut album, Blackened Sky,