Check out example codes for "facebook icon html5". It will help you in understanding the concepts better.

Code Example 1

<!-- Add icon library -->
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">

  
<!-- Add font awesome icons -->
<a href="#" class="fa fa-facebook"></a>
<a href="#" class="fa fa-twitter"></a>

  ...

Code Example 2

Refer link : 
https://www.programmingquest.com/2020/04/create-social-media-icon-using-html-css.html

<html>
	<head>
		<title>Social Media Icon Example</title>
		<!-- Adding font awesome icon library -->
		<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">
		<style>
			.fa {  
			  width: 25px;
			  padding: 20px;
			  font-size: 25px;
			  text-align: center;
			  text-decoration: none;
			  margin: 5px 2px;
			  color: white;
			  border-radius: 50%; 
			}

			.fa:hover {
				opacity: 0.7;
			}

			.fa-facebook {
			  background: #3B5998;
			}

			.fa-twitter {
			  background: #55ACEE;
			}

			.fa-google {
			  background: #dd4b39;
			}

			.fa-linkedin {
			  background: #007bb5;
			}

			.fa-youtube {
			  background: #bb0000;
			}

			.fa-instagram {
			  background: #8a3ab9;
			}

			.fa-whatsapp {
			  background: #4FCE5D;
			}

			.fa-pinterest {
			  background: #cb2027;
			}

			.fa-snapchat-ghost {
			  background: #fffc00;  
			  text-shadow: -1px 0 black, 0 1px black, 1px 0 black, 0 -1px black;
			}

			.fa-skype {
			  background: #00aff0;
			}

			.fa-github {
			  background: #000000;
			}

			.fa-dribbble {
			  background: #ea4c89;
			}

			.fa-vimeo {
			  background: #45bbff;
			}

			.fa-foursquare {
			  background: #45bbff;
			}

			.fa-stumbleupon {
			  background: #eb4924;
			}

			.fa-flickr {
			  background: #f40083;
			}

			.fa-yahoo {
			  background: #430297;
			}

			.fa-reddit {
			  background: #ff5700;
			}

			.fa-rss {
			  background: #ff6600;
			}
			</style>
	</head>
	<body>
		<!-- Using font awesome icons -->
		<a href="#" class="fa fa-facebook"></a>
		<a href="#" class="fa fa-twitter"></a>
		<a href="#" class="fa fa-google"></a>
		<a href="#" class="fa fa-linkedin"></a>
		<a href="#" class="fa fa-youtube"></a>
		<a href="#" class="fa fa-instagram"></a>
		<a href="#" class="fa fa-whatsapp"></a>
		<a href="#" class="fa fa-pinterest"></a>
		<a href="#" class="fa fa-snapchat-ghost"></a>
		<a href="#" class="fa fa-skype"></a>
		<a href="#" class="fa fa-github"></a>
		<a href="#" class="fa fa-dribbble"></a>
		<a href="#" class="fa fa-vimeo"></a>
		<a href="#" class="fa fa-foursquare"></a>
		<a href="#" class="fa fa-stumbleupon"></a>
		<a href="#" class="fa fa-flickr"></a>
		<a href="#" class="fa fa-yahoo"></a>
		<a href="#" class="fa fa-reddit"></a>
		<a href="#" class="fa fa-rss"></a>
	</body>
</html>

Code Example 3

<!-- Add icon library -->
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">

<!-- Add font awesome icons -->
<a href="#" class="fa fa-facebook"></a><a href="#" class="fa fa-twitter"></a>
  ...

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