In a nutshell, your Joomla site consists of two main parts: 

• The site's Joomla file system. 
• The site's database.

The database is where your Joomla system will be storing:

• The content you will be creating in your Joomla based site.
• Data referencing to your Joomla system settings.

Every time you write an article and save it, your Joomla system will send the article content to a specific part of your site database. 

If you unpublish currently published on your site certain article, this change will also be stored in a specific part of your site database.