title: what is the purpose and usage of data-value, data-title, data-original-title, original-title, etc.?
body: <p>I've been seeing these attributes around on more modern websites like GitHub and such, and they always seemed to coincide with a customized popover like the <code>title</code> attribute.</p>
  
  <pre><code>&lt;a href="/" data-value="hovering message"&gt;Option 1&lt;/a&gt;
  &lt;a href="/" data-title="hovering message"&gt;Option 2&lt;/a&gt;
  &lt;a href="/" data-original-title="hovering message"&gt;Option 3&lt;/a&gt;
  &lt;a href="/" original-title="hovering message"&gt;Option 4&lt;/a&gt;
  </code></pre>
  
  <p>I read some documents about data- attributes on HTML5 Doctor, and I'm not quite sure of the point.</p>
  
  <p>Is there some SEO or accessibility benefit to using them? And what is the plugin(hopefully jQuery) commonly being used to create the popovers in this specific case?</p>