The Port number is part of the URL, that means that you have to specify the port number always. But HTTP uses Port 80 as "default Port", so if you dont apply a port number, all browsers use Port 80. Therefore http://localhost:80
is exactly the same as http://localhost
BUT if you dont use Port 80, you cannot ommit the Port number, as the browser then again would take Port 80. So if you use Port 1234, you cannot ommit that port number, you must use http://localhost:1234
That is the reason, why we do not recommend to use a different Port for HTTP than Port 80. It looks quite ugly also.