An iterator is a programming construct that allows you to traverse through a collection of elements, such as lists or arrays, without needing to understand the underlying structure. It provides a way to access each element one at a time, making it easier to work with data in a sequential manner. Iterators are commonly used in many programming languages, including Python, Java, and JavaScript. In addition to simplifying data access, iterators help manage resources efficiently. They can be implemented using methods like `next()` to retrieve the next element and `hasNext()` to check if more elements are available. This design pattern promotes cleaner code and enhances performance by reducing memory overhead.