Introduction and Installation - Mastering phpMyAdmin 3.1 for Effective MySQL Management - page 9

Configuration principles
phpMyAdmin's behavior, given that no configuration file is present, has changed
in version 3.1.0. In versions 3.0 and earlier, the application used its default settings
as defined in libraries/config.default.php , and tried to connect to a MySQL
server on localhost —the same machine where the web server is running—with
user root and no password. This is the default setup produced by most MySQL
installation procedures, even though it is not really secure. However, if our freshly
installed MySQL server were still to have the default root account, we would have
logged on automatically and would have seen a warning given by phpMyAdmin
about such lack of security.
If the notion of MySQL root user eludes you, it might now be the
time to browse http://dev.mysql.com/doc/refman/5.1/en/
privilege-system.html , to learn the basics about MySQL's
privilege system.
Since version 3.1.0, the development team has wanted to promote a more
flexible login panel. This is why, in the situation of lacking a configuration file,
phpMyAdmin displays the cookie based login panel by default (more details
on this in Chapter 2):