Why does ICollection implement both IEnumerable and IEnumerable

Question

Why does ICollection implement both IEnumerable and IEnumerable?

What is the purpose of this? How does

Answer 1

The non-generic interface is for backward compatibility. If you write code using generics and want to pass your collection to some module written in .NET 1.0 (which doesn't have generics) you still want this to succeed, and you want the old method to be able to iterate through it.