Toolips are useful for adding in extra information, that doesn’t make sense always showing.

<span class="tooltip" data-tooltip-title="We aim to respond to support queries within 72 hours">
  <button class="btn btn--primary">Hover Me</button>
</span>

<span class="tooltip tooltip--light" data-tooltip-title="We aim to respond to support queries within 72 hours">
  <button class="btn btn--primary">Hover Me</button>
</span>