title: DbContext class, can't find
body: <p>please check this example <a href="http://www.asp.net/mvc/tutorials/getting-started-with-aspnet-mvc3/cs/adding-a-model" rel="nofollow">http://www.asp.net/mvc/tutorials/getting-started-with-aspnet-mvc3/cs/adding-a-model</a> and do tell me that where the "DbContext" class is from which MovieDbContext class has been copied. I can't find.
  this one:</p>
  
  <pre><code> public class MovieDBContext : DbContext 
   {
     public DbSet&lt;Movie&gt; Movies { get; set; } 
   }
  </code></pre>
  
  <p>and do tell me that what does DbSet means ? what it do ?</p>