Are the icons in built in the font awesome library of css? How do we get to use them

Answer 1

1.You can get the access to them by adding external link in your head section:

<!-- Font Awesome -->
<link rel="stylesheet" type="text/css" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">

For using them you must add this tag with attributes wherever you want:
<i class="fa THE_ICON_NAME"></i>
The icon names are in the font awesome webpage, in this section: http://fontawesome.io/icons/

2.Or you can simply download it in your computer. But no one recommends to do this.

Answer 2

icons are inside fa font file