https://fontawesome v4.7.0/ cdn http://maxcdn.bootstrapcdn.com/font-awesome/ code example
Example 1: font awesome 4.7 cdn
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css" integrity="sha256-eZrrJcwDc/3uDhsdt61sL2oOBY362qM3lon1gyExkL0=" crossorigin="anonymous" />
Example 2: fontawesome 4.7 cdn
<link href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.13.0/css/all.min.css" rel="stylesheet">