By default, Cascade pages are visible in the navigation. They can be marked in the metadata so as not to be included in the navigation and/or in the A to Z site map. If pages are not included in the navigation nor the site map, they are "invisible" to the site visitor. They can still be edited within Cascade.
There are several reasons for marking pages as invisible. There may be a functional reason that the page should only be accessed from another page. For example, the web visitor needs to read information before filling out or retrieving a form. So, the form's page may be marked invisible and be accessible only from a descriptive page. In addition, pages can be make invisible until they are approved by everyone or they can be marked to be visible in navigation but not included (visible) in the A to Z site map.
The change to these settings will take affect the next time the affected pages or the site are published.