Port: Number used to identify a process or application on a network.

Socket: A combination of an IP address and a port number

Port Forwarding: A method of routing data through additional ports.

When the www request packets arrive at the destination interface they need to be passed to the web server process.

Note: Most servers will be running a multitude of processes.

To enable that, packets’ content will have been labelled with a Port number before being sent.

The normal port number for web servers is 80.