In HTML, how to display favorite icon of a website

Almost all professional websites, need favorite icon, which will be displayed on top bar of the Browser.

Below is an example HTML code, on how to display favorite icon of a website.

<html>
<head>
<link rel="shortcut icon" href="./first.ico" />
<!-- ico is an image format used for icons 
Here gif and other img formats also can b used
-->
<title>Simple Title</title></head>
<body>
This is First HTML Page<br>
can u see this?
</body>
</html>