Why do I get an error instantiating an interface?

Question

I have a class and an interface, and when I try to instantiate the interface, I get an error:

Cannot create an instance of the abstract class or inter

Answer 1

You cannot instantiate an abstract class or interface. You must inherit it, if its an abstract class, or implement it if it's an interface. e.g.

...
private class User : IUser
{
  ...
}

User u = new User();