hover class in bootstrap 4 code example

Example 1: bootstrap 5 tooltip

<button type="button" class="btn btn-secondary" data-toggle="tooltip" data-placement="top" title="Tooltip on top">
  Tooltip on top
</button>
<button type="button" class="btn btn-secondary" data-toggle="tooltip" data-placement="right" title="Tooltip on right">
  Tooltip on right
</button>
<button type="button" class="btn btn-secondary" data-toggle="tooltip" data-placement="bottom" title="Tooltip on bottom">
  Tooltip on bottom
</button>
<button type="button" class="btn btn-secondary" data-toggle="tooltip" data-placement="left" title="Tooltip on left">
  Tooltip on left
</button>

<!-- With custom HTML -->
<button type="button" class="btn btn-secondary" data-toggle="tooltip" data-html="true" title="<em>Tooltip</em> <u>with</u> <b>HTML</b>">
  Tooltip with HTML
</button>

Example 2: bootstrap 4 class for hover

<div class="view overlay">
    <img src="https://mdbootstrap.com/img/Photos/Horizontal/City/6-col/img%20(3).jpg" class="img-fluid " alt="">
     <div class="mask rgba-red-strong">

    </div>
</div>