We might want to allow a single copy of phpMyAdmin to be used by a group of persons, each having their own MySQL username and password and seeing only the databases they have rights to. Or we might prefer to avoid having our username and password in clear text in config.inc.php.
Instead of relying on a username/password pair stored in config.inc.php, phpMyAdmin will communicate with the browser and get authentication data from it. This enables true login for all users defined in a specific MySQL server, without having to define them in the configuration file. There are three modes offered that allow a controlled login to MySQL via phpMyAdmin: http , cookie and signon. We will have to choose the one that suits our specific situation and environment (more on this in a moment). The http and cookie modes may require that we first define a control user.