Visual Basic 2015 Unleashed

The ViewState State

To provide support for the work that a page needs to do in its lifetime, ASP.NET provides a mechanism known as ViewState. It provides the infrastructure that serializes values for each control in the page. For example, when a page is rendered, a control has a particular value. When this value changes, and such change raises an event, ASP.NET makes a comparison between the ViewState and form variables so that it can update the control value. (The TextBox control with its TextChanged event is the most common example.) Such a mechanism is available behind the scenes, but you can also use the ViewState by yourself. The following is an example that makes an object available at page level:

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ViewState("MyPageDataKey") ...