C# .NET - Co variance and contra variance? - Asked By karur krishna madhu on 14-Apr-14 08:02 AM

Can someone explain what is this co variance and contra variance in plain terms? Short and simple

http://blogs.msdn.com/b/csharpfaq/archive/2010/02/16/covariance-and-contravariance-faq.aspx

First result in a Google search.  What part doesn't make sense?