title: What does it mean sha256 in Docker, where are directories of layers of image?
body: <p>I am newbie at Docker. I have to theoretically question about Docker.  We know that defaultly Docker uses AUFS, layers filesystem.  Where can I find in <code>/var/libs/docker</code> folders for each layer ?   I would like to see it. </p>
  
  <p>And second thing:<br>
  What is <code>sha256</code> ? I know that it is some number-hash. But what does it mean in docker ?</p>