how does div and class tag work in html code example

Example 1: div container style

<div class="tab-content col-md-12" 
style="	width:600px;
        box-shadow: 3px 3px 3px 3px grey;
        margin:10px;
        background-color: #E0D8D6;
      ">

Example 2: what is a div element in html

The <div> tag is nothing more than a container unit that encapsulates other page elements and divides the HTML document into sections.
 The div can be used for reading purposes or to nest all the information inside the div then to style the div through css as a background card.