Content Online / Offline
Content (page, articles) can be online and offline.
Set one content offline means this content is not reachable through its URL:
The website will return the 404 page.
When you're connected to the admin panel as "editor" or "admin", the offline content will be visible on the website.
This gives you a simple way to see how the content will look before putting it online.
Of course not connected users will not see this content online.