Removes irrelevant whitespace between HTML tags.

Template

{% spaceless %}
<p>
  <small class="text-muted">
    Created on: {{ joke.created }}
    Last updated: {{ joke.updated }}
  </small>
</p>
{% endspaceless %}

Result

<p><small class="text-muted">
    Created on: 
    Last updated: 
  </small></p>

Notice that the whitespace within the small element has not been removed. Only whitespace between successive opening tags and successive closing tags is removed.