The iterator design pattern is a commonly used pattern that provides a very useful abstraction. The iterator pattern is used to access and traverse the elements of a collection without the need to understand or expose the underlying structure of the collection.

Iterator is a behavioral design pattern in which you use an iterator to enumerate the elements of the container, i.e. the collection, in a sequential manner. Behavioral design patterns are those that manage object collaboration and the delegation of responsibilities among objects.

One of the advantages of the iterator pattern is that it allows you to modify the collection implementation without having to change the way the collection is accessed from the outside. As per the Dofactory, the Gang of Four defines the iterator design pattern as follows:

Provide a way to access the elements of an aggregate object sequentially without exposing its underlying representation.

In this article we will walk through a simple implementation of the iterator design pattern using C#. The participants in a typical implementation of the iterator pattern include the following: