FTP (File Transfer Protocol) is a client/server protocol that allows a user to transfer files to and from a remote network site. It works with TCP and is most commonly used on the Internet, although it can also be used on a LAN.
An FTP site is a computer that is running FTP server software (also known an FTP daemon, or
ftpd). A public ftp site can usually be accessed by anybody by logging in as
ftp. There are many excellent public ftp sites that make repositories of free Unix software available. By learning how to use FTP, you give yourself access to an indespensible resource.
Private FTP sites require a user name or password. If you have a shell account with your ISP, you may be able to access your files via FTP (contact your system administrator to check on this).
An FTP client is the userland application that provides access to FTP servers. There are many FTP clients available. Some are graphical, and some are text-based.
FTP was first developed by the University of California, Berkeley for inclusion in 4.2BSD (Berkeley Unix). The RFC (Request for Comments) is available at ftp://nic.merit.edu/documents/rfc/rfc0959.txt.