You may want to provide information for specific audiences.
If you create documents collaboratively, you may want to show some of the information on a page only to other team members who - for instance - have edit permissions for that page.
This is not about sensitive information! The content is hidden because it includes sections that need rework or show just an outline of what will get into. This information is intended for team members that work collaboratively on the documentation and is not useful for other audiences.
Another use case is to add additional information to a page that is again only relevant for a specific audience. Think of a list of documents that transclude content from a given page. This information may be very relevant for authors who apply changes to a document and want to lookup quickly all pages that reuse the changed content. This information is typically irrelevant for all other audiences. Therefore the list of references is only shown to page authors with edit privileges.
If you need to show some content on a page only for a specific audience, the hide macros may be very convenient: Hide From Anonymous User Macro or Hide From Reader Macro.
In addition to that the Section Macro and Content Marker Macro provides parameters that help to hide the page fragment.
Note the word 'hide'
The fragment is still on the page and can be accessed by anyone. This is because the page can be fetched in its storage format easily.
So do not hide sensitive information on a page. The hide feature is simply a convenience for the reader.
If you actually need to secure information then you probably need to install a third-party add-on.
