Single-File Page Model

I refer to http://msdn.microsoft.com/en-us/library/015103yb.aspx.
I have run successfully with html and code on the same page.  However I am curious how the page load event handler gets called.  I have the following in my aspx page:
<%@ Page Language="C#"%>
<script runat='server'>
  protected void Page_Load(object sender, EventArgs e)
    { ... }
</script>
 
Who calls Page_Load?  Is this method with a hard-coded name always called automatically when the page is loaded?
Thanks.
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