cdnjs font awesome

CSS
<link href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.13.0/css/all.min.css" rel="stylesheet"><link  rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.13.1/css/all.min.css"><link rel="stylesheet" href="path/to/font-awesome/css/font-awesome.min.css">
<link rel="stylesheet" href="https://pro.fontawesome.com/releases/v5.10.0/css/all.css" integrity="sha384-AYmEC3Yw5cVb3ZcuHtOA93w35dYTsvhLPVnYs9eStHfGJvOvKxVfELGroGkvsg+p" crossorigin="anonymous"/><link rel="stylesheet" href="https://pro.fontawesome.com/releases/v5.10.0/css/all.css" integrity="sha384-AYmEC3Yw5cVb3ZcuHtOA93w35dYTsvhLPVnYs9eStHfGJvOvKxVfELGroGkvsg+p" crossorigin="anonymous"/>
OR
<link href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css" rel="stylesheet" integrity="sha384-wvfXpqpZZVQGK6TAh5PVlGOfQNHSoD2xbE+QkPxCAFlNEevoEH3Sl0sibVcOQVnN" crossorigin="anonymous">
gem 'font-awesome-sass'
Source