I'm trying to educate myself a little more about web standards and protocols, and at the same time I'm involved in a little project on the same subject.

I have a question about something I came across in the Wikipedia article for HTTPS. In the third paragraph of the Overview, there's a part that talks about how HTTPS encrypts everything but the port numbers and the IP address of the server. I would assume the former, since doesn't HTTPS always communicate over port 443? But what about the second part? How exactly would that be exposed? How would an intruder get that information? If the IP address for the server is retrieved as part of the DNS process, wouldn't the URL also be visible?

Okay, I'm sure I have a very loose understanding of the stuff I was saying in that last paragraph. I'm happy to be set straight. But basically I'm looking for some source that states the elements that HTTPS doesn't encrypt, if anything.