Use the TreeNode.ChildNodes property to get a System.Web.UI.WebControls.TreeNodeCollection collection that contains the first-level child nodes of the current node. This collection is commonly used to iterate through all the first-level child nodes, or to access a specific first-level child node of the current node.

The TreeNode.ChildNodes property can also be used to programmatically manage the first-level child nodes in the current node. You can add, insert, remove, and retrieve System.Web.UI.WebControls.TreeNode objects from the collection. Any updates to the collection will automatically be reflected in the System.Web.UI.WebControls.TreeView control the next time the page is refreshed.

To access child nodes further down the tree, use the TreeNode.ChildNodes property of the next-level child node to navigate down the node levels.