title: How to add alt text to background images? Making background images accessible
body: <p>I have a site that is displaying many of its images as background images using <code>background-size: cover</code> to size them to completely fill the element while cropping off any parts of the image that don't fit.</p>
  
  <p>The problem is that these images are NOT purely decorative. They are a critical part of the informational content of the page. This means they need <code>alt</code> text in order to be accessible to screen readers and other assistive technologies.</p>
  
  <p>What is the most semantic way to add <code>alt</code> descriptions to background images?</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>article {
    position: relative;
    width: 320px;
    margin: 5rem auto;
  }
  
  figure {
    width: 100%;
    height: 180px;
    /* not accessible */
    background-image: url('http://www.fillmurray.com/300/300');
    background-size: cover;
    background-position: center;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;link href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet" /&gt;
  
  &lt;article class="panel panel-default"&gt;
    &lt;header class="panel-heading"&gt;
      &lt;h4 class="panel-title"&gt;Title of Article&lt;/h4&gt;
    &lt;/header&gt;
    &lt;div class="panel-body"&gt;
      &lt;figure class="article-image"&gt;&lt;/figure&gt;
    &lt;/div&gt;
    &lt;footer class="panel-footer"&gt;
      &lt;a class="btn btn-default" href="#"&gt;Read&lt;/a&gt;
    &lt;/footer&gt;
  &lt;/article&gt;</code></pre>
  </div>
  </div>
  </p>