Search notes:

System.Collection.IList (interface)

System.Collection.IList is the base interface for all non-generic lists. The generic counterpart is System.Collections.Generic.IList<T>.
System.Collection.IList implements System.Collections.ICollection.
There are three types of classes that implement IList:
A prominent class that is not in the System.Collections namespace and still implements IList is System.Array.

Index