Other ports may be specified by adding a colon and the port number after the computer name, ie. Your browser then formats the page for display on your screen. Several of our pages are encrypted during transmission for security purposes. The mechanics of SSL are too complex for this discussion, but suffice it to say it works almost transparently to the user. What is important is that your browser now communicates on Port 443 instead of Port 80.
Many networks use a firewall to protect the network from attack by outside sources.
If the firewall is not set up to allow access to other internet ports, you will not be able to connect to a secure site or sites using anything other than Port 80. You tell if a link is going to a secure site by placing your cursor over the link and looking at the status bar at the bottom of your browser.