If your database server is on a different server, enter the host name or IP address here.
If you are using shared web hosting, your hosting provider should give you the correct host name in their documentation.
If you are using MySQL, using "localhost" may not work for the server name. If it does not, try "127.0.0.1" for the local IP address.
If you are using PostgreSQL, leave this field blank to connect via a Unix socket.