There are a lot of maintenance related tasks which need to be executed regularly for your site to function correctly. These tasks are executed with the help of the so called 'cron' program (under Unix) or 'scheduled tasks' (under Windows).
The main task ({output.basepath}/tools/cron/cron.php) has to run
every 5 minutes.
The command to be run by cron is:
{output.phpbin} -f {output.basepath}/tools/cron/cron.php
Please note that the path to the php binary could not be detected automatically. You need to replace "{output.phpbin}" in the command above with the actual path.
Also check out the available documentation on this subject.