title: How to choose between `class` and `id`
body: <p>When using <code>divs</code> when is it best to use a <code>class</code> vs <code>id</code>? </p>
  
  <p>Is it best to use <code>class</code>, on say font variant or elements within the html? Then use <code>id</code> for the structure/containers? </p>
  
  <p>This is something I've always been a little uncertain on, any help would  be great.</p>