Gangnam Style: What does it mean?

Rapper Psy has become the first South Korean pop star to make it to the top of the UK singles chart with his song Gangnam Style.

The track has become a global phenomenon and the video featuring his famous horse-riding dance is YouTube's most "liked" of all time, but does anyone know what Gangnam Style actually means?

The BBC's Lizo Mzimba has been investigating the story behind the sensation.