SSH (Secure Shell) is a protocol for encrypting and securing various kinds of data transfers over a network or the Internet. SSH works by opening a secure channel between the SSH server and an authenticated user's computer. Many kinds of data may be sent or retrieved through this channel.
SSH can be understood as a large pipe: its purpose is to carry whatever is passed through it from one place to another without letting anything leak in or out.
SFTP operates nearly identically to FTP, but all transmissions are secured under the SSH protocol. Select WS_FTP Server packages are available with SFTP (Secure File Transfer Protocol) over SSH2 to transfer files.