ListIn this example, we create a list of integers and add three integer elements to it. Then, we use the Add method to add another integer element to the list. The package library for the IEnumerable Add method is "System.Collections.Generic". This package contains a set of classes and interfaces that provide a generic collection framework. It is part of the standard .NET framework and can be used in any C# project.myInts = new List { 1, 2, 3 }; myInts.Add(4);