Check out example codes for "font awesome css". It will help you in understanding the concepts better.

Code Example 1

<!-- Add this in your <head> tag -->
<link
      rel="stylesheet"
      href="https://use.fontawesome.com/releases/v5.13.0/css/all.css"
      integrity="sha384-Bfad6CLCknfcloXFOyFnlgtENryhrpZCe29RTifKEixXQZ38WheV+i/6YWSzkz3V"
      crossorigin="anonymous"
    />

Code Example 2

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

Code Example 3

<span style="font-size: 3em; color: Tomato;">
  <i class="fas fa-camera"></i>
</span>

<span style="font-size: 48px; color: Dodgerblue;">
  <i class="fas fa-camera"></i>
</span>

<span style="font-size: 3rem;">
  <span style="color: Mediumslateblue;">
  <i class="fas fa-camera"></i>
  </span>
</span>

Code Example 4

<i class="fa fa-plus" aria-hidden="true"></i>

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