Pro C# 2010 and the .NET 4 Platform, Fifth Edition

32.14. The Life Cycle of an ASP.NET Web Page

Every ASP.NET web page has a fixed life cycle. When the ASP.NET runtime receives an incoming request for a given *.aspx file, the associated System.Web.UI.Page-derived type is allocated into memory using the type's default constructor. After this point, the framework will automatically fire a series of events. By default, the Load event is automatically accounted for, where you can add your custom code:

public partial class _Default : System.Web.UI.Page
{
  protected void Page_Load(object sender, EventArgs e)
  {
    Response.Write("Load event fired!");
  }
}

Beyond the Load event, a given Page is able to intercept any of the core events in Table 32-8, which are listed in the order in which they are encountered ...