Westlife is an Irish pop group formed on 3 July 1998. The group's original lineup comprised Mark Feehily, Shane Filan,Kian Egan, Nicky Byrne and Brian McFadden. McFadden left in 2004. The group is the only act in UK history to have their first seven singles go straight to Number 1, and they have gone on to sell over 44 million records worldwide^[1] which includes their studio, single, video, and compilation albums.^[2][3] Despite the group's worldwide success, they've only had one U.S. hit on the Billboard Hot 100 charts: "Swear It Again," which made it to #20 in 2000.

Westlife were originally signed by Simon Cowell and are currently managed by Louis Walsh. In 2008, they were declared as Ireland's ninth-richest celebrities under 30 years old and 13th in general with 36 million euros as a group.^[4] In 2009, they dropped as 16th richest Irish with estimated 8 million euros each.^[5] They garnered 14 number one singles in the United Kingdom, the third-highest in UK history, tying with Cliff Richard and trailing behind only Elvis Presley and The Beatles. The group has also broken a few top records, including "Music artist with most consecutive number 1's in the UK". It was officially announced by Music Week that they are the "2nd biggest selling artist" (trailing behind Robbie Williams) and "Biggest selling band of the decade" (beating Coldplay) in UK with 10.14 million album sales. At the same time, their very own song "Evergreen" was hailed as the top selling single in the UK of the decade (2000-2010). (See Westlife records)

Though none of Westlife's members play an instrument full-time, all of them knows how to play an instrument/s. Over years of their career, Westlife's music has evolved from teen pop to a pop sound, with an emphasis on ballads. Most of the group's hits have been composed by experienced songwriters, most notably Steve Mac and Wayne Hector. (See Songs written)

On 1 June 2008, Westlife marked their 10th anniversary with a concert in Croke Park, Dublin which saw more than 83,000 fans attending the special occasion. Music Week revealed on their website that Westlife is the official third top touring act within the years 2005–2008, while they were 7th top touring act of 2008.^[6]