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The Iterator pattern gives clients a uniform way to inspect and consume the elements of a collection without exposing how that collection is stored. An iterator has a traversal state separate from the abstract collection interface, so the same client loop can process an array, a linked list or generated values. It preserves encapsulation and representation independence: changing the underlying data structure need not change the traversal client. Separate iterator instances can track separate traversals; two aliases of one consuming iterator instead share its progress.

The iterator pattern exposes sequential traversal through a small interface while hiding the representation of the underlying data. A client asks whether another entry is available and requests the next entry; it need not know whether the producer uses an array, linked list, tree or generated sequence.

The key design benefit is encapsulation of traversal state and representation. The same consuming algorithm can work through the interface for different producers, and each traversal can keep its own cursor state when a fresh iterator is supplied. This independence requires separate consumption states; two references to one iterator share a cursor.