What has always puzzled me, is the number of successful songwriting teams that have existed in the last century. I can think of a few form the 19th century, too. Who writes first, the lyricist or the composer? How much do they work together, and how much is independent?
I suppose the answer has already been posted - "it depends." Still, it seems so strange to me that pairs of individuals can be so successful at songwriting.

-Joe-