They are an a cappella group that formed for the 3rd season of The Sing Off (an a cappella competition), for which they won among other prizes a Sony record contract. Since then, they have released a few albums, had a part in the movie
Perfect Pitch 2, and won a Grammy for best Instrumental or A Cappella group for their song
"Daft Punk" which is an arrangement that has several songs by the group Daft Punk. Their Xmas album
That's Christmas to Me was certified gold last year, and has been the most successful Xmas album since 1962. This year's self-titled album debuted #1 in Billboards Top 200 (albums) chart.
I've actually been a fan of theirs since I first saw them on
The Sing Off, and have enjoyed many of their songs. Although most of their songs are a cappella arrangements of other popular songs, I'm glad to see that they are moving onto more original songs, with their first original single being released earlier this fall;
"Can't Sleep Love" reached #99 in Billboard's Hot 100 chart.