To ensure that your site and its modules continue to function well, a group of administrative operations should be run periodically. These operations are called cron tasks. Examples of cron tasks are: checking for module and theme updates, indexing content for search, or cleaning up temporary files.
Linux/Unix-based operating systems have a cron scheduler that can be used to run periodic tasks. You can use the server’s cron scheduler to schedule runs of the site’s cron tasks. Alternatively, you can use the core Automated Cron module to run tasks. You can check the site’s cron tasks' status in the status report.