Cron automated tasks

The term 'Cron' refers to the automated tasks that a site runs periodically. It takes care of tasks such as checking if updates are available for Drupal core, contributed modules, and themes. Another example is sending a hundred emails every ten minutes from midnight to three in the morning every weekday.

By default 'Cron' runs every three hours. Other options are available, from 1 hour to 1 week. You can run cron anytime from either the "Status report" page available from "Reports" > "Status report" page or from the "Cron" page, available from "Configuration" > "System" > "Cron". 

Contributed modules are available for additional cron functions.

Or use your server's Cpanel (or similar). You can run it on certain minutes, hours or days, or within a range, like  weekends or night midnight to 5 in the morning, see related for cron's flexibility and usefulness.