Abba was a Swedish pop group formed in the 1970s that became one of the most successful and iconic music groups of all time. The group consisted of Agnetha Fältskog, Björn Ulvaeus, Benny Andersson, and Anni-Frid Lyngstad. They achieved international success with their catchy pop songs and unique sound, selling over 380 million records worldwide. ABBA is known for hits such as 'Dancing Queen, ' 'Mamma Mia, ' and 'Take a Chance on Me.'