Check out example codes for "class in html". It will help you in understanding the concepts better.

Code Example 1

<ul class="legend">
    <li><span class="greendot"></span>Text</li><br></br>
    <li><span class="yellowdot"></span>Text</li><br></br>
    <li><span class="reddot"></span>Text</li><br></br>
    <li><span class="blackdot"></span>Text</li><br></br>
</ul>

Code Example 2

<p class="ThisIsAClassName">HI</p>

Code Example 3

<p class="ClassExample">ClassExample!!</p>

Code Example 4

<!-- 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 5

<h1 class="write a name">H1 content</h1>

Code Example 6

<!DOCTYPE html>
<html>
<head>
<style>

  .city {
  background-color: tomato;
  color: white;
  
  border: 2px solid black;
  margin: 20px;

    padding: 20px;
} 
</style>

 </head>
<body>

<div class="city">

  
 <h2>London</h2>
  <p>London is the capital of England.</p>

 </div>

<div class="city">

  
 <h2>Paris</h2>
  <p>Paris is the capital of France.</p>
</div>

<div class="city">

  
 <h2>Tokyo</h2>
  <p>Tokyo is the capital of Japan.</p>
</div>

</body>
</html>

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