Ftp is a way of transfering files from one computer to another. Most often this is done to transfer files from your commputer to an Internet server. This is often so you can upload a file to the Web so other people can download it.
You can do this with an Ftp Program. You normally need to know A) the host address of the other computer - eg - ftp.clearerchannel.org B) your username C) a pass word.