FTPS (also known as FTP-ES, FTP-SSL and FTP Secure) is an extension to the commonly used File Transfer Protocol (FTP) that adds support for the Transport Layer Security (TLS) and the Secure Sockets Layer (SSL) cryptographic protocols.
FTPS should not be confused with the SSH File Transfer Protocol (SFTP), an incompatible secure file transfer subsystem for the Secure Shell (SSH) protocol. It is also different from Secure FTP, the practice of tunneling FTP through an SSH connection.
Read more about FTPS: Background, Methods of Invoking Security, Firewall Incompatibilities