title: Is C# 4.0 backward compatible to C# 2.0?
body: <p>May I know what is the difference between C# 4.0 and C# 2.0? Is C# 4.0 backward compatible to C# 2.0?</p>
  
  <p>Can I say that C# 4.0 is a superset of C# 2.0 (just like what C++ is to C)?</p>
  
  <p>Thanks.</p>