In fact, domain names and IP addresses correspond, and this correspondence is called mapping. The website we visit with domain name is a hypertext protocol, and its public port number is 80, which means that in most cases, we visit the website rather than other services. So in fact, this port number can be omitted by default, and of course there is the port number 443 of the encrypted web service. Fortunately, these two ports can be omitted by default. By default, when you request, the browser will carry the number 80 or 443 according to the protocol itself. Of course, it is no problem to add the port number manually.
If your port number is special, not 80 or 443, then you need to tell the browser the port number of the thing I requested. If you don't tell the browser, the default is 80 or 443, then if the service port number provided by your server is not 80 or 443, you can't discard the request, which is determined by the standard used by * * *, not by the browser or the server. Unless you open the browser and the penetration rate is high, you may omit different ports, otherwise you can only change the service port number of the server to 80 or 443, so you don't have to write this port.