FTP is a protocol created in 1980 (RFC959) to transfer files to different servers and networks. typically over a WAN connection.
However, it is not a service you should use to host sensitive information. The following is why,
FTP does not perform encryption on transit; Anyone between you and the FTP server can, will, and most likely have been monitoring and logging traffic.
FTP does not securely communicate credentials; FTP does not encrypt authentication, this means that passwords are in plain text and can be READ BY ANYONE monitoring your network.