From the official 'Scotland' website
The History and Words of Auld Lang Syne
It is one of the many folk songs from the great Lowland Scots tradition collected and fashioned by the pen of one of the world's greatest songwriters. Burns devoted the last years of his life to the song tradition, and often a mere fragment from some old ballad was transformed by his alchemy into a memorable love song or Scots poem. With Auld Lang Syne, though, the brilliance was already there; this is the Bard's first mention of it in a letter to Mrs Dunlop in 1788:
Jim Carroll