title: Confusion about complete binary tree
body: <p>I keep seeing it defined as </p>
  
  <blockquote>
    <p>A complete binary tree is a binary tree in which every level, except
    possibly the last, is completely filled, and all nodes are as far left
    as possible.</p>
  </blockquote>
  
  <p>But..I have no clue as to what it means by "all nodes are as far left as possible." That's..literally my question. I can't expand on it any further because I have no idea what it means by "all nodes are as far left as possible." Like..as far left as possible compared to what? I don't get it</p>