how the server side identifies button click event

hi i have one doubt of button click in asp.net, i have placed the button control with the OnClick event like <asp:Button ID="mybutton" runat="server" Text="Insert" onclick="mybutton_Click" /> and some other controls(buttons, textboxes) in .aspx page. When i run the page, the button displays in the page source of the browser like <input type="submit" name="mybutton" value="Insert" id="mybutton" /> here, it does not display the onclick event, then how the page calls the button click on the server side, how the server side identify which button cause the submit, and how this page moves to the server side.