Talking shop?

What exactly are Party Conferences for?  At present it's the Labour conference, but I'm sure the Conservative conference, whenever it is, will be much the same.  Talk about preaching to the converted!  Just a load of speeches saying how great we are, and how terrible the other lot are.  Nothing really positive comes out of them and it's unlikely that anybody's views are ever changed as a result, so, like I say, what are they for?