ASP.net: EnableViewState when, why on what control

<asp:Label ID="ErrorMessageLabel" EnableViewState="false" runat="server" />

<asp:Label ID="TitleLabel" runat="server" Text="Update this Employee" />

If Not IsPostBack AndAlso myEmployeeObject.IsNew Then TitleLabel.Text = "Create a new Employee"

<asp:Label ID="TitleLabel" runat="server" Text="Update this Employee" EnableViewState="false" />

If myEmployeeObject.IsNew Then TitleLabel.Text = "Create a new Employee"

void Button1_Click()
{
   label1.text += " more!";
}