View state is the method that the ASP.NET page framework uses to preserve page and control values between round trips . When the HTML markup for the page is rendered, the current state of the page and values that must be retained during postback are serialized into base64-encoded strings.
Read moreWhat is IsPostBack in ASP.NET with example?
IsPostBack is a property of the Asp.Net page that tells whether or not the page is on its initial load or if a user has perform a button on your web page that has caused the page to post back to itself. The value of the Page.
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