It is an image with size of 20px x 20px, displayed left in title bar of web browser. For favicon image ico, png, jpg, gif, svg file format can be used.

<!DOCTYPE html>
<html>
<head>
  <title>Favicon example</title>
  <link rel="icon" type="image/x-icon" href="favicon.ico">
</head>
<body>
</body>
</html>

Link tag is used to add favicon to website and must be placed in head section.