Hierarchies

Hierarchies must be applied with care.

They should be as flat as possible and their use must not result in loss of context.

In the previous example the user never loses site of the levels of hierarchy because the Site Map Area and the Entry Point Area never disappear.

On the other hand, the conventional way of navigating via hierarchies goes something like this:

The diagram represents six "hits" into a hierarchy.

On the Web each linked page completely overlays the previous.

Imagine each new page stacked on top of the previous. In the end you would have a stack of six pages with the item of interest hidden on the bottom of the pile. Curious. Most people prefer that the things they want be on top of the pile.