Cerberus FTP and Complete FTP is a couple of commercial FTP servers. FileZilla is an open-source freeware FTP server that also provides a free FTP client. Some of the other popular FTP clients are WinSCP, Transmit, FireFTP and Cyberduck.
FTP is a widely used method to transfer files over a network. FTP clients today have excellent graphical user interfaces. File transfers are seamless and just a matter of drag and drop.