Several standard controls are included with default.master that provide the basic infrastructure for navigation. For example, the ASP.NET SiteMapPath control that has been positioned at the very top of the page populates a breadcrumb navigation menu that allows users to navigate from the current site upward to the parent site and all the way to the top-level site of the current site collection. 

        <p>
        Navigation in WSS is based on the navigation-provider infrastructure introduced in ASP.NET 2.0. In this model, a navigation provider is designed and created to provide a set of navigation nodes. In many cases, the nodes supplied by a navigation provider can be bound to a <b>menu control</b> or a <b>treeview</b> to give users a user interface component with which to navigate around the site.
        </p>

        <p>
        WSS provides several standard navigation providers such as the <b>SPNavigationProvider</b>, <b>SPSiteMapProvider</b>, <b>SPContentMapProvider</b>, and <b>SPXmlContentMapProvider</b> classes. You can see where all the active navigation providers are defined by examining the siteMap section inside the system.web section of the standard WSS web.config file.
        </p>

        <p>
        The top link bar and the Quick Launch menu represent the two main navigation components defined in default.master. The top link bar is defined by using a WSS-specific control of type AspMenu along with a SiteMapDataSource control that is configured to point to the standard SPNavigationProvider component. The Quick Launch menu is defined in the same way. The major difference between the two is that the SiteMapDataSource for the top link bar is configured with a StartingNodeUrl attribute with a value of sid:1002, whereas the Quick Launch menu is configured with a StartingNodeUrl attribute with a value of sid:1025.
        </p>
        <p>
        The next question you should be asking is what the significance is between 1002 and 1025. It has to do with the data stored in the content database for tracking navigation nodes. The top node for the top link bar has an ID of 1002, and the top node to the Quick Launch menu has an ID of 1025.

        WSS provides users with the flexibility to add navigation nodes to either the top link bar or the Quick Launch menu. You can access the application pages that allow users to perform these actions from the Site Settings page. What’s nice about this scheme for developers is that you can customize the standard WSS navigation menus without making any changes to default.master. You simply need to find a way to add new navigation nodes to the content database.

        While it’s possible for users to add navigation nodes through site administration pages in the browser-based user interface, it’s also possible and far more flexible to accomplish the same goal by using the WSS object model. The CustomSitePages feature provides code in the FeatureActivated event handler to add navigation nodes to construct a custom drop-down menu in a fashion that is not possible to replicate through the user interface. Examine the following code and observe how it creates SPNavigationNode objects and adds them to the collection of nodes that define the structure for the top link bar.


        </p>

        <pre data-sub="prettyprint:_">
        public override void FeatureActivated(SPFeatureReceiverProperties properties) {

        // get a hold of current site in context of feature activation
        SPWeb site = (SPWeb)properties.Feature.Parent;
        SPNavigationNodeCollection topNav = site.Navigation.TopNavigationBar;

        // create dropdown menu for custom site pages
        SPNavigationNode DropDownMenu1;
        DropDownMenu1 = new SPNavigationNode("Site Pages", "", false);
        topNav[0].Children.AddAsLast(DropDownMenu1);

        // add navigation nodes to create menu items
        DropDownMenu1.Children.AddAsLast(
        new SPNavigationNode( "Site Page 1",
        "SitePages/Page01.aspx"));
        DropDownMenu1.Children.AddAsLast(
        new SPNavigationNode("Site Page 2",
        "SitePages/Page02.aspx"));
        }

        </pre>