title: Docker, what is it and what is the purpose
body: <p>I've heard about Docker some days ago and wanted to go across.</p>
  
  <p>But in fact, I don't know what is the purpose of this "container"? </p>
  
  <p>What is a container?</p>
  
  <p>Can it replace a virtual machine dedicated to development?</p>
  
  <p>What is the purpose, in simple words, of using Docker in companies? The main advantage?</p>