FTPS File Transfer, FTP Secure or FTP-SSL as it can be referred to, is a secure means of sending data over a network. Often misidentified as SFTP (an independent communications protocol in its own right), FTPS describes the sending of data using basic FTP run over a cryptographic protocol such as SSL (Secure Socket Layers) or TLS (Transport Layer Security). The default port for FTPS is Port 21 for explicit mode or Port 990 for implicit mode .
Cryptographic protocols ensure that sections of the connection established between a client and server are encrypted, thus maintaining the security and integrity of the data sent. They similarly use a public/private key authentication system to encrypt data before it is sent and decrypt it once it has been received. Therefore if the data stream were interrupted during transmission, any documents in transit would be illegible to hackers or eavesdroppers.