When must we use extern alias keyword in C#?

Question

When must we use extern alias keyword in C#?

Answer 1

Basically you only really need it when you want to use two types with the same fully qualified name (same namespace, same type name) from different assemblies. You declare a different alias for each assembly, so you can then reference them via that alias.

Needless to say, you should try to avoid getting into that situation to start with :)