Port Checker

Server Applications use well-known ports such as 80, 443, etc. (well-known ports). Almost all of the ports on 80 (HTTP packets) uses for the webserver and 443 (https) for encrypted traffic. User registered ports(1024-49151) is used on p2p applications such as torrent, skype, etc.
To request a webpage from the internet, we need to use port 80 because it is the default port listener of the web. The port also needs to be open by the firewall so the request can go out. Ports also can be used on DNS or IP addresses because when you request via DNS:port, the computer will automatically translate it into IP address:port.
How to find Port Numbers?
You can use cmd to find ports. via cmd, you can type netstat -a and it will check the running ports on specific addresses.
With this tool, You can check if your port is open and can be accessed it allows you to know if the IP port is open on your connection. You can try to use google.com on hostname and port 80 and click submit. On that request, you will see if the port is open or close.