Provide a way to access the elements of an aggregate object sequentially without exposing its underlying representation.
In object-oriented programming, the iterator pattern is a design pattern in which an iterator is used to traverse a container and access the container's elements. The iterator pattern decouples algorithms from containers; in some cases, algorithms are necessarily container-specific and thus cannot be decoupled.
Iterators that traverse all elements of a container, very often, form the base for more specific Iterators that allow for filtering. The .NET Framework Linq to Objects is a good example of that.