Hidden fields and ViewState (C#) : HiddenField « ASP.net Controls « ASP.NET Tutorial

<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"  "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
    <title>Hidden Fields and ViewState</title>
    <form id="form1" runat="server">
        <asp:TextBox ID="TextBox1" Runat="server"></asp:TextBox>
        <asp:Button ID="Button1" Runat="server" Text="Button"  />
        <asp:HiddenField ID="HiddenField1" Runat="server" />

File: Default.aspx.cs

using System;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;

public class Person
    public string firstName;
    public string lastName;

public partial class _Default : System.Web.UI.Page
    protected void Page_Load(object sender, EventArgs e)
        if (!Page.IsPostBack)
            HiddenField1.Value = "foo";
            ViewState["AnotherHiddenValue"] = "bar";

            Person p = new Person();
            p.firstName = "Scott";
            p.lastName = "Hanselman";
            ViewState["HiddenPerson"] = p;

3.18.1.Working with the HiddenField server control (C#)
3.18.2.Working with the HiddenField server control (VB)
3.18.3.Hidden fields and ViewState (C#)
3.18.4.Hidden fields and ViewState (VB)
3.18.5.Use hidden field to pass value