Roots of Alex & Sierra

A Great Big World is an American musical duo from New York made up of singer/songwriters Ian Axel and Chad King. The group is best known for their single "This Is the New Year", which was performed by the cast in an episode of Glee and reached the Billboard Mainstream Top 40 chart in May 2013, and their worldwide hit "Say Something", particularly after recording it as a duet collaboration with Christina Aguilera. The duet peaked at number four on the Billboard Hot 100.

Christina María Aguilera is an American singer, songwriter, actress, and television personality. An influential figure in music, Aguilera is noted for her four-octave vocal range, melismatic singing style, use of the whistle register, and continual reinvention of her image and sound. Referred to as the "Voice of a Generation", she was ranked among the greatest singers of all time by Rolling Stone. Her works have incorporated socially conscious and sexual themes, generating both controversy and critical acclaim.

Of Monsters and Men is an Icelandic indie folk/rock band formed in Garðabær in 2010. It consists of lead singer and guitarist Nanna Bryndís Hilmarsdóttir, singer and guitarist Ragnar "Raggi" Þórhallsson, lead guitarist Brynjar Leifsson, drummer Arnar Rósenkranz Hilmarsson, and bassist Kristján Páll Kristjánsson.

Sara Beth Bareilles is an American singer, songwriter, musician, and actress. She has sold over three million albums and over 15 million singles in the United States. Bareilles has earned various accolades, including two Grammy Awards, as well as nominations for four Primetime Emmy Awards and three Tony Awards. In 2012, VH1 named her one of the Top 100 Greatest Women in Music.