SFTP, FTP, and SCP are the three file transfer protocols supported by WinSCP. SSH is used by SFTP and SCP, making them secure.  FTPS is a secure version of FTP. To begin with, be sure the server you're connecting to is a secure server — WinSCP only protects a single file transfer session from server to client and client to server. You are not safe if your server still has an open FTP or Telnet port.