As your site grows, you may want to clean up the site contents. You probably don't want to display outdated articles—such as last year's news—among your current content. In Joomla, there are different ways to achieve this. One option is to unpublish old articles. That way, the articles are still available in the backend, but the site visitor cannot see them anymore. Another option is to create an archive. Archived articles are still available, but they're no longer part of the "ordinary" site contents. You can make them visible through a menu link of the Archived Articles menu item type.
Archiving is something you do by hand. To archive an article (or multiple articles at once), select the desired article(s) in the Article Manager and hit the Archive toolbar button.
Tip
If you want to automatically archive articles that are older than a given period of time, consider using Joomla extensions such as Auto-Archive. You can find it on the Joomla extension site (http://extensions...