Default Tooltip 
<button type="button" class="btn btn-secondary" title="Default tooltip" data-toggle="tooltip">  ...</button>
Tooltip Placement 
<button type="button" class="btn btn-secondary" title="Default tooltip" data-toggle="tooltip" data-placement="top">  ...</button>
Attr Keys
data-placement="*" top | right | bottom | left
Tooltip HTML 
<button type="button" class="btn btn-secondary" data-toggle="tooltip" data-html="true" title="<em>Tooltip</em> <u>with</u> <b>HTML</b>">  ...</button>
Disabled Element 
<span class="d-inline-block" tabindex="0" data-toggle="tooltip" title="Disabled tooltip">  <button class="btn btn-primary" style="pointer-events: none;" type="button" disabled>  ...  </button></span>