What does localhost:8080 mean? [closed]

Question

What is the difference between localhost/web vs. localhost:8080/web?

Answer 1

A TCP/IP connection is always made to an IP address (you can think of an IP-address as the address of a certain computer, even if that is not always the case) and a specific (logical, not physical) port on that address.

Usually one port is coupled to a specific process or "service" on the target computer. Some port numbers are standardized, like 80 for http, 25 for smtp and so on. Because of that standardization you usually don't need to put port numbers into your web adresses.

So if you say something like http://www.stackoverflow.com, the part "stackoverflow.com" resolves to an IP address (in my case 64.34.119.12) and because my browser knows the standard it tries to connect to port 80 on that address. Thus this is the same as http://www.stackoverflow.com:80.

But there is nothing that stops a process to listen for http requests on another port, like 12434, 4711 or 8080. Usually (as in your case) this is used for debugging purposes to not intermingle with another process (like IIS) already listening to port 80 on the same machine.

Note from 2021: When I made this post, I used port 80 as example because even though the OP didn't specify a protocol, http was the usual web request standard back then and 80 ist the standard for http. Nowadays pretty much everything runs on https and the standard port for that is 443.

Answer 2

localhost/web is equal to localhost:80/web OR to 127.0.0.1:80/web

localhost:8080/web is equal to localhost:8080/web OR to 127.0.0.1:8080/web