title: What are abstract classes and abstract methods?
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/1320745/abstract-class-in-java">Abstract class in Java</a>  </p>
  </blockquote>
  
  
  
  <p>I got several explanations but so far I'm not able to understand that what are the abstract classes and methods in Java.</p>
  
  <p>Some said it has to do something with the security of the program, other said it isn't anything like that.</p>
  
  <p>Even from the Dietel &amp; Dietel's book I don't get it's purpose. 
  When,where and why do we use it?</p>
  
  <p>Kindly explain it like you're teaching a beginner, I would really appreciate your help.</p>