How browser identifies the difference between asp and html buttons

Hi all,

 While clicking an ASP button, the page refreshes. But while doing the same with a HTML button without a runat="server" attribute, the page doesnot refresh. Eventhough at the browser, these controls are rendered as "<input type=button>", How does the browser identifies the difference between the two (how the browser identifies that on clicking the ASP button, the page has to refresh and on clicking the HTML button, it shouldnt)?
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