title: What is a 'group' or 'group address' as related to sockets and networking?
body: <p>This one is awfully tough to Google. I found in code a structure like this:</p>
  
  <pre><code>  socket_info_a {
      address: "206.xxx.xxx.xx"
      group: "10.13.xxx.0/0"
      port: "7000"
      username: "foo"
      password: "bar"
    }
  </code></pre>
  
  <p>The x's all had actual numbers.</p>
  
  <p>What is the group portion and why is it there?</p>