Check out example codes for "how to choose your html website favicon". It will help you in understanding the concepts better.

Code Example 1

<!DOCTYPE html 
      PUBLIC "-//W3C//DTD HTML 4.01//EN"
      "http://www.w3.org/TR/html4/strict.dtd">
<html lang="en-US">
<head profile="http://www.w3.org/2005/10/profile">
<link rel="icon" 
      type="image/png" 
      href="http://example.com/myicon.png">
[…]
</head>
[…]
</html>

Learn ReactJs, React Native from akashmittal.com