In computing, the SSH File Transfer Protocol (sometimes called Secure File Transfer Protocol or SFTP) is a network protocol that implements file transfer between computers. It is often used as more secure alternative of an FTP protocol, which transmits file contents, folder contents and even passwords without encryption.
SFTP protocol is built on top of SSH protocol which is used as a transport layer over the port 22 and is implemented by an SSH server such as OpenSSH. SFTP is different from SCP, which is another protocol relying on an SSH connection. It is also different from FTPS, which used SSL to encrypt the connection itself, rather than sending the data through an SSH tunnel.
Many popular FTP programs have added support for SFTP. Access to the SFTP server can be granted either through a username, a password or by using a public key.