A navigation model defines the elements and hierarchy of a navigation. It allows you to control which elements are added and specify the metadata for those resources.
In WebCenter, you can have different navigation models. This way you can customize the model for specific needs. For example, you can create a navigation model for people who are working in the Finance department and a completely different model for people from the HR department.
Navigation models can have links to pages, external links, links to external applications, portlets, taskflows, and so on. You can include almost every resource in a navigation model.
WebCenter lets you manage navigation models both at design time and runtime. This way, it is very easy for administrators who manage the portal to edit the navigation models.