From a computer’s point of a view, a site is just a collection of pages.
From a visitor’s point of view, these pages have a structure: a site has a home page, categories, subcategories, and so on.
The site tree
We can represent this structure using a site tree — a diagram of pages that resembles a family tree.
For example, a site tree for a simple site selling furniture and appliances might look like this:
We use the same terminology as for family trees:
A page directly under another in the site tree.
In the example above, Furniture and Appliances are children of Kitchen.
The page directly above another in the site tree.
In the example, Products is the parent of Kitchen.
A page directly or indirectly above another in the site tree.
The home page is an ancestor of all pages.
In the example, Products and Home are the ancestors of Kitchen.
A page with the same parent as another page.
In the example, Lounge and Dining room are siblings of Kitchen.
The children of the home page are called top-level pages.
Most sites have two types of top-level page:
Top-level content pages
Top-level pages without children.
In the example above, About us and Contact us are top-level content pages.
Top-level category pages
Top-level pages with children.
In the example, Products is the only top-level category page.
If there are not many top-level pages, they may be shown in a single area of navigation.
If there are a lot of top-level pages, they are usually shown in two areas of navigation: an area for top-level content pages, often at the top of each page, and an area for top-level category pages, often between the header and the page content.