If I understand right, applications sometimes use HTTP to send messages, since using other ports is liable to cause firewall problems. But how does that work without conflicting with other applications such as web-browsers? In fact how do multiple browsers running at once not conflict? Do they all monitor the port and get notified... can you share a port in this way?

I have a feeling this is a dumb question, but not something I ever thought of before, and in other cases I've seen problems when 2 apps are configured to use the same port.