Imagine an organization with a few departments. Each worker should be capable to read the posts of its own department plus the posts general for all organization. Some workers of each department should be capable to create/edit posts of their own department only. Guests (not logged-in visitors) should view only general posts and should not view restricted posts related to the departments.
Such task difficult for the “just-from-the-box” WordPress may be resolved easy with User Role Editor Pro content view and edit restrictions add-ons configured together. Read more View and Edit restrictions – complex example