title: Does git "dirty" mean files not staged, or not committed? (glossary conflict)
body: <p><a href="https://www.kernel.org/pub/software/scm/git/docs/gitglossary.html#def_dirty" rel="noreferrer">https://www.kernel.org/pub/software/scm/git/docs/gitglossary.html#def_dirty</a>
  A working tree is said to be "dirty" if it contains modifications which have not been committed to the current branch.</p>
  
  <p><a href="http://www.gitguys.com/topics/glossary/" rel="noreferrer">http://www.gitguys.com/topics/glossary/</a>
  Dirty working directory
  If files have been updated in the working directory after they were updated in the index then the working directory is considered “dirty”. The working directory is clean if all modified files in the working directory have been added to the index.</p>
  
  <p>If I understand correctly, the "index" is also known as the "staging area" and is a place where files will be stored (copied to? symlinked?) when you have changed them, want to commit them, but haven't done a commit yet. (The first glossary says the staging area can also be used for merging. The second glossary says files are moved there by 'git add'.)</p>
  
  <p>So the two glossaries seem to be saying incompatible things. Which is correct? Or is there some way they could both be correct?</p>