What is an FTP port?

In this context, a port is a term used when referring to the location of FTP sites - it is an essential extension of the address used to access them. This port number is tacked onto the end of the address in the form ':564'.

A real life equivalent of trying to access an FTP site using the wrong port number would be going to the right building to retrieve something, but then wandering around aimlessly on the wrong floor. The result: you won't find what you are looking for, most likely because the door you eventually knock on is the wrong one.

If an FTP site is not assigned with a specific port number, it will use the default value of 21.

Port numbers, nevertheless, are also used to access other forms of computer communication software such as email clients, instant messengers and so on. It is wise to close off access to those ports which are not currently in use using a firewall. This prevents hackers from gaining access to your system - see the anonymity tutorial for further details.