Tooltips
These modular elements can be readily used and customized in every layout across pages.
For detail documentation, View Tooltips on Bootstrap
Example
<button class="btn btn-secondary btn-sm m-1" type="button" data-toggle="tooltip" data-placement="top" title="Tooltip on top">Tooltip on top</button>
<button class="btn btn-secondary btn-sm m-1" type="button" data-toggle="tooltip" data-placement="right" title="Tooltip on right">Tooltip on right</button>
<button class="btn btn-secondary btn-sm m-1" type="button" data-toggle="tooltip" data-placement="bottom" title="Tooltip on bottom">Tooltip on bottom</button>
<button class="btn btn-secondary btn-sm m-1" type="button" data-toggle="tooltip" data-placement="left" title="Tooltip on left">Tooltip on left</button>
<button class="btn btn-secondary btn-sm m-1" type="button" data-toggle="tooltip" data-html="true" title="<em>Tooltip</em> <u>with</u> <b>HTML</b>">Tooltip with HTML</button>