[A] Formed on 3 July 1998, the group was made up of singers Nicky Byrne, Kian Egan, Mark Feehily, Shane Filan, and Brian McFadden (who quit the band on 9 March 2004).

The last four members remained active until their last live concert performance in the Europe's third largest stadium Croke Park on 23 June 2012 and have reunited on 3 October 2018 for new music and tour.

[2] In 2012, the Official Charts Company listed Westlife 34th amongst the biggest-selling singles artists in British music history.

This earned them the following Guinness World Records: first to achieve seven consecutive number-one singles in the UK, most singles to debut at number one on the UK chart and top selling album group in the United Kingdom in the 21st century.

However, "Swear It Again" was the band's first number-one single in the United Kingdom and Ireland followed by seventeen more number-ones from their succeeding singles "If I Let You Go", "Flying Without Wings", "I Have A Dream/Seasons in the Sun", "Fool Again", "Against All Odds (Take a Look at Me Now)", "My Love", "Uptown Girl", "Queen of My Heart"/"When You're Looking Like That",[B] "World of Our Own", "Unbreakable", "Tonight"/"Miss You Nights", "Mandy", "Everybody Hurts",[C] "You Raise Me Up", "The Rose", "Hello My Love",[D] and "Dynamite"[E] from 1999 to 2019.