Port

The same computer can have several programs related to the network. Therefore they get one or more ports each. This is used e.g. when another computer wants to talk to a certain program, and then asks for the relevant port.
The ports are simply numbers, between 0 and 65536. 0-1024 are special. HTTP typically uses port 80, FTP uses port 21, and email (SMTP) port 25.

Concept last updated: 15/09 2003.