System.Web.UI Namespace
Manages the view state of ASP.NET server controls, including pages. This class cannot be inherited.
View state for a page or control is the cumulative propery values, or view, of that page or control. You can access this class through the Control.ViewState property.
This class is the primary storage mechanism for all HTML and Web server controls. It stores attribute/value pairs as strings associated with the control. It tracks changes to these attributes only after the method that handles the Init event is executed for a page request, and save the changes to the page's or control's view state.
You can read from this class during any stage of the control processing lifecycle, but you should not write to it while the control is rendering.
This class implements a dictionary, and you can add or remove items from it as you would any dictionary object.