title: What is AF_INET, and why do I need it?
body: <p>I'm getting started on socket programming, and I keep seeing this <code>AF_INET</code>.</p>
  
  <p>Yet, I've never seen anything else used in its place. My lecturers are not that helpful and just say "You just need it".</p>
  
  <p>So my questions:</p>
  
  <ul>
  <li>What is the purpose of <code>AF_INET</code>?</li>
  <li>Is anything else ever used instead of it?
  
  <ul>
  <li>If not, why is it there? For possible changes in the future?</li>
  <li>If so, what and why?</li>
  </ul></li>
  </ul>