If you haven’t discovered what CRON is yet… Check this out first.
When you run CRON it runs a collection of tasks.
You can see what these tasks are by going to the Scheduled tasks list.
Site administration > Server > Scheduled tasks
By turning on Allow ‘Run now’ for scheduled tasks in the administration settings, you can individually run a scheduled task rather than re-running all the tasks using CRON.
Alternatively, you can set new tasks schedules if required.
This would only be necessary if you are using plugins that access external services.
Site setting screen shot for scheduled tasks below.