Check out example codes for "class html". It will help you in understanding the concepts better.
Code Example 1
<p class="ClassExample">ClassExample!!</p>
Code Example 2
<h1 class="write a name">H1 content</h1>
Code Example 3
<!-- in the head element -->
<style> h1 { color:blue; } </style>
<!-- in the body element -->
<h1> text in blue because all "h1" element is in blue </h1>
Code Example 4
<p class="ThisIsAClassName">HI</p>
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