A Fragment in Android is a reusable and modular section of an activity’s user interface and behavior that can be combined with other fragments to create a dynamic and flexible application layout. It represents a portion of the screen in an activity and has its own lifecycle, layout, and input handling. Fragments were introduced to support more dynamic and adaptable UI designs, especially for devices with different screen sizes such as smartphones and tablets. Unlike an activity, a fragment cannot exist independently and must be hosted by an activity. The activity acts as a container, while the fragment defines and manages its own UI and logic within that container. Fragments help developers build modular applications. Instead of designing a single large activity to handle all UI components and logic, developers can divide the interface into multiple fragments, each responsible for a specific part of the screen or functionality. For example, in a news application, one fragment can display a list of news headlines, and another fragment can display the detailed content of a selected headline. On a mobile phone, these fragments may appear one at a time, while on a tablet, both fragments can be displayed side by side. This adaptability is one of the key advantages of using fragments. The lifecycle of a fragment is closely related to the lifecycle of its host activity, but it has its own distinct set of callback methods that manage its creation, display, and destruction. Understanding the fragment lifecycle is essential for developing stable and efficient Android applications. The fragment lifecycle begins with