Server Control View State

View state is a fancy name for ASP.NET storing some state data in a hidden input field inside the generated page. When the page is posted back to the server, the server can parse, validate, and apply this view state data back to the page's tree of controls. View state is a very powerful capability since it allows state to be persisted with the client and it requires no cookies or server memory to save this state. Many ASP.NET server controls use view state to persist settings made during interactions with elements on the page, for example, saving the current page that is being displayed when paging through data.
There are a number of drawbacks to the use of view state, however. First of all, it increases the total payload of the page both when served and when requested. There is also an additional overhead incurred when serializing or deserializing view state data that is posted back to the server. Lastly, view state increases the memory allocations on the server.
Several server controls, the most well known of which is the DataGrid, tend to make excessive use of view state, even in cases where it is not needed. The default behavior of the ViewState property is enabled, but if you don't need it, you can turn it off at the control or page level. Within a control, you simply set the EnableViewState property to false, or you can set it globally within the page using this setting:

<%@ Page EnableViewState="false" %>

If you are not doing postbacks in a page or are always regenerating the controls on a page on each request, you should disable view state at the page level.