In TALK, you can organize pages into a hierarchy of parent and child pages. Pages in such a hierarchy are called a 'page family'.
Page families are a simple but effective way of categorising content and making navigation of your site easier by providing links forward and backwards through the page hierarchy.
A parent page is at the topmost level of that hierarchy.
For example, within the TALK Help space, the hierarchy of pages looks like this:

The 'Home' page in this hierarchy is the parent page and the 'Creating...', 'Get Started' and 'TALKing...' pages (plus others) are its child pages. Together, they comprise a page family.
TALK will only allow you to create page families that are a simple tree. What this means is that you can create any number of nested families but a child can have only one parent.
You can view the hierarchy that the current page sits in by clicking on Page Information in the menu or sidebar. Locate the page Hieracrhy section. More information available on the page information page.
Page Tree
To see the hierachy of ALL the pages in a space click on the Space Map option in the Space Operations menu.
Child Pages
You can see the child pages of the current page by scrolling to the bottom of the page. Any children will be listed.