title: What are the difference between col-lg and col-md in bootstrap3
body: <p>What are the difference between <code>col-lg</code>, <code>col-md</code> ,<code>col-xs</code> and <code>col-sm</code> grid system in in <em>bootstrap 3</em>.</p>
  
  <p>In a bootstrap template they used <code>&lt;div class="col-lg-6 col-md-6 col-xs-12 col-sm-6"&gt;&lt;/div&gt;</code> only for one column grid.  I am a beginner in Bootstrap.</p>