title: Why do you need a base image with Docker?
body: <p>I have went through every single page of the documentation of <a href="http://www.docker.io">Docker</a>. </p>
  
  <p>I do not understand, yet still, why a "base image" (for example, the Ubuntu Base Image) is necessary to furnish the containers before installing/creating an application environment.</p>
  
  <p>My questions:</p>
  
  <ul>
  <li>What is a base image and why is it required?</li>
  <li>Why is it not possible to just to create a container and put the application in it similar to virtualenv of Python?</li>
  </ul>