title: Can you explain Docker with a practical example/case?
body: <p>I have read <a href="https://stackoverflow.com/questions/16047306/how-is-docker-io-different-from-a-normal-virtual-machine">this</a> and the <a href="https://www.docker.com/whatisdocker/" rel="nofollow noreferrer">intro docs on Docker.io</a> and I like the concept it presents. But, can you help me understand it a little better? Can you give me some practical examples and/or case studies on how Docker is used and when it makes sense to actually use it?</p>
  
  <p>Just a side note, I have recently started using Vagrant to distribute a preconfigured DEV box to our development team (so we all use the same base system). I have even seen examples where Docker is used inside Vagrant and whatnot but I don't get what are the benefits to do this in a practical sense; meaning that I understand the difference between VMs and containers and the logical separation the latter provide, but when should I use the one instead of the other and when Docker <em>inside</em> Vagrant? (this is a more specific question but I am mostly interested in the bigger picture as outlined in the first question above).</p>