Explicit SSL is also known as Auth SSL or Auth TLS. With explicit SSL, the default FTP server port is used, normally port 21. Both SSL and non-SSL connections can be made on this port. Auto FTP Manager will send a command to the FTP server to start the SSL connection.

With Implicit SSL, the security is always on. A dedicated port, usually port 990, is used for secure connections.

If you are installing a new FTP server, you can use either implicit or explicit SSL. If you choose implicit, you will need to assign a separate port number. Auto FTP Manager will auto-detect whether explicit SSL or implicit SSL is used on your FTP server.