File eXchange Protocol - This refers to server to server transfer. You can transfer files from one pub to another using very little of your own bandwidth. This is by far the best means for distributing large files, only problem is that a very limited number of FXP capable pubs exist.
FXP stands for "File eXchange Protocol," and is a way to transfer files directly betwen two FTP servers without moving the files to your Macintosh (the client) first. In Fetch, FXP is referred to as "direct server-to-server transfers." See the server-to-server transfers help topic for more information.