title: What do the numbers on a Git Diff header mean?
body: <p>Every time I run git diff, for each single changes I made, I get some sort of header with numbers, for example:</p>
  
  <pre><code>@@ -169,14 +167,12 @@ function Browser(window, document, body, XHR, $log) {.....
  </code></pre>
  
  <p>I wonder what does the four numbers mean? I guess -169 means that this particular line of code that follows was originally in line 169 but now is in 167? And what do 14 and 12 mean?</p>