title: What does "checkout head" do?
body: <p>I tried the following out of curiosity:</p>
  
  <pre><code>git checkout head
  </code></pre>
  
  <p>And I got this:</p>
  
  <pre><code>$ git checkout head
  Note: checking out 'head'.
  You are in 'detached HEAD' state.
  
  Me@MyPC /c/repo ((9da1bd7...))
  $
  </code></pre>
  
  <p>Whereas</p>
  
  <pre><code>git checkout HEAD
  </code></pre>
  
  <p>does nothing (as expected).
  So what exactly is the former command doing?</p>
  
  <p>More info: Yes, I am on Windows. And it did not create a tag or a branch as far as I can tell:</p>
  
  <pre><code>Me@MyPC /c/repo ((9da1bd7...))
  $ git log -n 1
  commit 9da1bd740434923ae55ca1b50efb7c62eb6e0c35
  Author: someone else
  Date:   Fri Dec 6 15:44:08 2013 +0100
  
  Me@MyPC /c/repo ((9da1bd7...))
  $ git tag -l
  TestRelease
  
  Me@MyPC /c/repo ((9da1bd7...))
  $ git branch -l
  * (detached from head)
    master
  </code></pre>