Can u Explain Exception Handling Techniques in ASP.NET 2005 using error events?

There are three different error events in ASP.NET that can be used in conjunction with SEH so that all exceptions are handled and the user is presented with a user-friendly error message.
1. Page_Error: Occurs when an error occurs within the Web page. This event is in the Web form.
2. Global_Error: Occurs when an error occurs within the application. This event is in the Gloabl.asax file.
3. Application_Error: Occurs when an error occurs within the application. This event is in the Gloabl.asax file.
Methods in the Server object are used to handle the exception in the error events.
1. GetLastError: Gets the last exception that occurred on the server.
2. ClearError: Use this method to handle the exception and stop the error to trigger the subsequent error event or display the error to the user.
In the following code, you handle the exception in all the above three mentioned events but call the ClearError method only in the Application_Error event so that the error is propogated to the above level.
private void Page_Error(object sender, System.EventArgs e)
{
Exception ex = Server.GetLastError();
Response.Write("Handled error from Page<br>");
//Server.ClearError();
}
protected void Application_Error(Object sender, EventArgs e)
{
Exception ex = Server.GetLastError();
Response.Write("Handled error from Application <br>");
Server.ClearError();
}
protected void Global_Error(Object sender, EventArgs e)
{
Exception ex = Server.GetLastError();
Response.Write("Handled error from Global <br>");
}