<link rel="icon" type="image/x-icon" href="favicon.ico"> code example
Example 1: html favicon.ico
<! -- For .ico files -->
<link rel="shortcut icon" href="favicon.ico" type="image/x-icon">
<! -- For .jpg/.gif/.png files -->
<link rel="icon" type="image/gif/png" href="favicon.png">
Example 2: png favicon
<link rel="icon" type="image/png" href="logo.png" />