I fell over a really nice and friendly introductionary article on curl and libcurl, written by M. Tim Jones, on IBM’s developerWorks site.

I must confess I greatly enjoyed his image showing the network layers and how curl/libcurl fits into the general picture:

While of course arguably there is no ‘socket layer’ (as sockets are a pure API) I still think pictures like this serves a good purpose helping to explain how things interconnect. I personally really suck at visualizing things with images so I’m happy when I see this nice work I can borrow ideas from!