title: How is Polymorphism and Abstract class implemented/used in the .NET Framework or ASP.NET
body: <p>I am not able to understand the usage of Polymorphism and Abstract classes in the .NET Framework or ASP.NET. I know what Polymorphism means after reading various articles on the internet, however, they are generic (or it may seem to me). But I am not able to co-relate that to something concrete in .NET. For eg, why is a particular class in the .NET Framework marked as ABSTRACT. If someone can explain that, I would be in a better position to understand its need. Likewise for Polymorphism.</p>
  
  <p>I hope I am clear in what I am asking and would love to get some really good explanation.</p>
  
  <p>Thank you</p>