As your website grows - you have created more articles you might decide that some of your articles can be left published but archived.
For example you might create an article each month about what has happened over the previous month for a particular topic, theme, or issue.
Previous months articles on that topic, theme, or issue can be archived.
Your Joomla Archive module shows a list of the calendar months containing archived articles so that your website visitors can still access thos articles..
After you have changed the status of an article to archived, this list will be automatically generated.