View State is one of the most important and useful client side state management mechanisms. It can store the page value at the time of post back (Sending and Receiving information from Server) of your page. ASP.NET pages provide the View State property as a built-in structure for automatically storing values between multiple requests for the same page.
we generally used “EnableViewState” Properties for both Page Level and Server Control Level to maintain the view state. Till ASP.NET 3.5 Version, Page Level view state control treat as highest priorities. Which means If we set EnableViewState= “False” in page level that will automatically derived by all the server side control. In that case if we set “EnableViewState=”True”” for any server side control will treat as false, as we have defined them “False” in Page Level.Here is one complete article on ASP.NET 2.0/3.5 View State , which may helpful for you
Now, let’s have a look into the changes in ViewState Control in ASP.NET 4.0. There is a massive change in View State Control in ASP.NET 4.0 which is very much helpful for developer also. Asp.net 4.0 added a new property to Page object and server controls called ViewStateMode.