I can't understand,
when ISPs block all your external IP's ports and the incoming traffic
on them, then how it is possible to open a web page and request
information from it, and then the web page server can send the
information (incoming traffic) to your external IP and you get the
information without being blocked.
I login to facebook and facebook server sends to my computer's
the html code of the home page.
How can this information pass the block of the ISP???