title: What does role="button" mean?
body: <p>I found that in Google+ Project's page that buttons are all made from divs like:</p>
  <pre><code>&lt;div role=&quot;button&quot;&gt;&lt;/div&gt;  
  </code></pre>
  <p>I'd  like to know, is this just for semantic purposes, or does it influence the style or event handling of the <code>&lt;div&gt;</code>?</p>
  <p>I tried to simulate a button &quot;click&quot; with the jQuery <code>click</code> event, but it didn't work.</p>