C# 4.0 brought support for Dynamic, a pretty damn big change. And of course optional and default parameters, another huge boon. Then C# 5.0 brought Async, a hu

C# 4.0 brought support for Dynamic, a pretty damn big change. And of course optional and default parameters, another huge boon. Then C# 5.0 brought Async, a huge feature. In terms of making the language more powerful I would call those on par with extending out extension methods.