Intent

Page Object encapsulates the UI, hiding the underlying UI widgetry of an application (commonly a web application) and providing an application-specific API to allow the manipulation of UI components required for tests. In doing so, it allows the test class itself to focus on the test logic instead.

Class diagram

Applicability

Use the Page Object pattern when

You are writing automated tests for your web application and you want to separate the UI manipulation required for the tests from the actual test logic.
Make your tests less brittle, and more readable and robust

Credits