You may never have heard of Girls Generation, but they have beaten Justin Bieber, Selena Gomez, One Direction, Lady Gaga, Psy, Miley Cyrus and Demi Lovato to win the YouTube Music Awards' Video of the Year for their song I Got A Boy.

Girls Generation is a South Korean girl group formed by SM Entertainment in 2007. The nine-member group comprises Taeyeon, Jessica, Sunny, Tiffany, Hyoyeon, Yuri, Sooyoung, Yoona and Seohyun.

Their look and sound are pretty and preppy: short skirts, big smiles, jazz hands and that irresistible K Pop sound. Girls Generation is huge in Korea and Japan - so huge that Katy Perry and Miley Cyrus must envy their album sales.

In 2009, the group's hit single Gee was named South Korea's Song of the Decade.

Even so, their win in the inaugural YouTube Music Awards, held in New York on Sunday evening, surprised many.

The awards were based on YouTube data (including "shares", "like" and "most watched") from the past 12 months.

Eminem won Artist of the Year, beating Psy, Katy Perry, Rihanna, Justin Bieber, Nicki Minaj, the Epic Rap Battles of History duo (Peter Skukoff and Lloyd Ahlquist), Taylor Swift, One Direction, Macklemore and Ryan Lewis.

Cyrus was notably missing from the Artist of the Year nominees.

A clip of Girls Generation collecting their award was up on the internet as a "gif" (graphic interchange format) within minutes of it occurring.