what is treenode.tag means

tag gives you a means by which you can attach any value or some specifier which can distinctly identify or seperate out a tree node.

 

Let's say you have a tree view with 3 level structure like state wise, city wise, customer names.

 

Now you want to keep a track of all nodes which are at state level, all nodes which are at city level, all nodes which are at customer (3rd level)

 

how do you identify those? simply when you create those nodes, also assign tag property as "state", "city" or "customer", so later when let's say user clicks on a particular treeview node, then from reading its tag property you can identify if a state, city or customer type treeview item is clicked.